Over the past five years I've been buying really high quality bases on ebay from Hong Kong and China. I know there are many made in America enthusiasts here but in this case these slotta bases put not only third party slotta bases to shame, but GW as well. Many third party bases have grainy, rough sides and are thin and structurally weak. These are thicker, the sides are glossy, and they are machined such that the only sprue mark is on the underside. A variety of sellers that come and go sell them, but they can often be found with the words "Ver. 3.0" or similar in the title.
Example:
"Table Board Games 25mm Round Close Base x 100 PCS (Ver. 3.0)"
A few months ago I found myself in need of several hundred 25mm square bases and it's a strange thing, all the other sizes are to be had, including the new 32mm round, but not 25mm square. It's understandable that the demand for 25mm square diminishes now that GW has switched to 32mm round, but it doesn't make sense that demand would shrivel to the point where it was no longer worth making them. 20mm square are still easily at hand.
I'm guessing no one can provide a ready solution for me, and I guess mainly I'm just voicing my frustration. I have a bunch of third party 25mm bases that don't meet my standard, or don't fit with my others, and I have some very old GW ones that I actually save for when a particular trait they have is called for… they're the old kind with the open diagonal slot and the closed straight slot you can pop out with a screwdriver, and the straight slot is a bit closer to the back edge than more recent straight slot only bases… and some old Citadel figures are positioned such that they are too far forward when put on the newer kind, but perfectly centered when put in the farther back slot. As these aren't to be had for any price anymore, I'm not going to use them where another base will do just as well.
I went as far as to ask one seller about 25mm squares, but got no reply. Just a really frustrating cause of a halt to a planned project!
Though I suppose if anyone has tons of 25mm square GW ones lying around and you've switched to 32mm round, please get in touch, They aren't as nice but they will do!