Firstly there's the one that I can justify to my wife! It's a learning tool for the kids honest..
At about £7 a week it's sort of affordable but at 90 issues it's going to be while before it's finished. The specs are ok, so should be a good general purpose printer and it has a decent size print area.
Next up indestructibles.com
The first one is a nice design by a 13 year old in Canada! I've most of this built barring a couple of 3d printed parts that I need to order. Again it has a decent print area so it should be a good general purpose printer.
To print the required catch22 parts for these and anything else where you don't have a 3d printer I've used https://www.3dprint-uk.co.uk/. I would recommend them as they are pretty cheap and the quality is really good.
Lastly a 3d SLA printer. I really wish I hadn't seen this one since I haven't finished the other two yet. I've already purchased the DLP projector. £9 with some minor display spots. Seeing the quality of the pieces the creator has printed, I need to get this working soon. Having the ability to quickly create control panels, tank tracks, hatches and engines will be a huge bonus. I'll be able to spend even more time with the kids looking an the unfinished commercial 3d printer.
If you have been using a 3d printer in your scratch building I'd really like to hear your experiences good or bad.