>>11232726I've never used them but one Anon talks about his occasionally. I just use buckets of water and dish detergent but if you have one already they apparently work well.
>Is it cheaperIt depends, if you're patient you can pick up great deals much cheaper than buying anything new, and with the superior old Lego quality. Plus resale value if you ever decide to sell it. But if you're looking for grey bricks specifically, I would say just buy by the kg from Webrick. White, yellow, and red are common enough in older lots (90s and earlier) but greys are much less common. Check out Bricklink to compare the prices of different basic brick colours.
I would say just shop around to see what there is in your area first.
