I have picked up a few LEGO store displays in the past and the best ones for me are the ones that just contain minifigures from a particular theme.
Below is the most recent that I have picked up: DC & Marvel Superhero’s
I have seen two versions of this, one with 24 Minifigures (12 DC & 12 Marvel), and the other like this one with 26 Minifigures (14 DC & 12 Marvel).

I also have a few Star Wars ones, and all 3 versions of the Yoda Star Wars Minifigure only display ( the 3 different versions, contain the same minifigure selection, but have either LED lights in it, standard display, or slim line display.
Below is a image of my Slim Line version:

And although I gave this post a LEGO Store display Minifigure title, I have one of my favourites below, again this is a Star Wars Yoda display, but this time with a few extra items included.. plus LED show. This was from the US, with hard plexiglass.


Any more collectors out there? With LEGO store Minifigure displays.. (I know there are 3 more Star Wars Minifigure only ones, and I have seen a Lord Of The Rings display ( I did purchase some of these other ones but they arrived in bad shape.... )
Comments
That's one way of doing it, but you'll want to make sure it's an open window, otherwise you're likely to set off alarms and arouse suspicion when the glass breaks.
They also don't ship well.
Any of of the Perspex display cases are very difficult to keep in good condition so it looks like you've done well so far. I wish I knew my local Lego store employees better - perhaps it's because 'local' is around 3 hours and £40 away for me.
And as @SumoLego mentioned they don’t ship very well. So getting these to the UK can be very hard.. And costly when they arrived broken, as it’s very hard to claim against the shipping company!
I also know of someone selling 4 x large Star Wars French minifigure displays, some brand new and in box, for just under €3K. And will ship them to the UK. (These are hard to find like this).
Thats if you have the space to display them... I don’t have the space to display, and don’t want to get them to just put them in storage.. PM me if interested and I’ll pass on the details.
TLG.... the dream crushers....
19” Darth Vader with Lights and motion.
They are also the sort of thing that if you want to buy a specific one at a specific time, then they can be expensive. Whereas if you want to sell, they can be cheap unless you can find the right buyer.
Star Wars Rogue One 48” Display: $300-350
Batman Movie 48” display: $300
Marvel Super Hero’s shelf tube figure display (I haven’t seen this one before): $125-150. But if a few come to market then the price can reduce.
The others i.e. Lego City, Friends have less value, and probably will not get very much in an eBay auction. If you have the original shipping boxes it helps.
And if you have any brand new in wrap and shipping box, then these sell better.
Only downside to these is shipping (cost and being fragile) and also if you do a pickup only then you reduce you potential sales down.
If you have anything else you want rough prices for, I’m sure there are experts in every LEGO field on the forum, which can help you know the right price.
If they allow sales booths, I would consider getting a van or U-Haul and taking all of your items to sell at this show (assuming they allow sales)....
https://www.brickuniverse.com/columbia
You might want to get a list of (what sounds like only MINT) LEGO sets you want to sell, as well as all the displays... and sell it all at this location.
You can check the Brickset or Bricklink sites (or Ebay) to determine what the sets are worth... and if you were to go to such a convention... you could hypothetically unload all of your late husbands LEGO sets. You might find this preferable to a slow process of selling items on Ebay... which involves a lot of packaging, shipping and the headaches of bad arrivals (UPS used your sets/displays as footballs).
Just something to think about... since this convention is a month away.
These are display pieces that aren't supposed to make it to eBay or the secondary market. I've never seen any markings indicating a manufacturer for the tube. Whether from TRU or Target, they're supposed to be destroyed when a new plan-o-gram or section reset occurs. (Obviously, this doesn't always happen.)
However, the tubes of this era are the same. I would say over the last five years, the minifig tubes have been consistent. The one below was made in 2014. There are Ninjago, Friends, TLBM, etc. that are a similar form factor. The caps seem replaceable - just no idea where you would be able to find one. Maybe someone has a less-desirable theme and you could get an undamaged tube and swap the caps.
Cheers
The one on eBay is not in 100% best condition, but all the pieces are there, and it just needs a touch of TLC. The plexi glass looks good which is the main thing.
https://www.ebay.co.uk/itm/Lego-Star-Wars-technic-Shop-Display-Case/153394448377?hash=item23b70587f9:g:4K4AAOSw19dcdBPV
If I didn’t already have the other one then I would have taken this one.. ;)
(Or floating in the ocean as a microplastic thread in the Great Pacific Garbage Patch. If you're jaded in that way. To each their own, whatever.)
http://raumhafen.de/cgi-bin/showp.pl?pic=/galerie/lego_displays/2015_75102m&titel=Lego%20Star%20Wars%20Store%20Display%2075102%20Motion%202015
It’s a very hard to find LEGO store display, very happy with it. 😀
They will be hard to display all together, as the US ones you have fix to the shelf a different way to the EU ones.
With the marvel US ones I have I was thinking about using one of my bigger displays, and have the shelf display underneath.
Cheers