A cheap ebay plant will likely be cracked. Useful for spares, depending on how much comes with it, but 50/50 on whether it'll ever run well. You can get two or three and put together a good one, which is what some people do.
Decent ones cost as much as a complete Disco (logic being it's the only good part, apart from running gear, which is cheap as chips and probably knackered anyway), so 90% we'd pick up a breaker and swap it out. That way you get all the ancillaries with it, bearing in mind none of your existing will be compatible, and presuming spares will be similarly inflated on your side of the pond.
Shipping would be the real issue. Can't be cheap for a block + parts, or a broken Disco. Neither are small or light, as you know, but if you can get over that (shipping company? Bear in mind these lots are always pickup-only), might as well import a few and make your money back.