How many albums do you have to be converted?
The only reason I ask is that you've made some pretty big leaps in the couple of days since starting this thread. I think you have a good understanding that the quality you'll get will be directly proportional to the money you spend, and that getting decent results won't be cheap.
Pro-ject is a well respected turntable manufacturer. Their range includes some really good budget turntables. The
Debut III USB is perfect for your job and Superfi sell it at about the cheapest price - £259 delivered. You then need a decent'ish sound card and some cables - M-Audio 2496 is pretty good without breaking the bank - £55-£65.
OK, in theory you've spent about £320, you've got a nice turntable but it is only fitted with a £20 'starter' cartridge. Hardly the highest of fidelity items, but it's the same story with all the budget t/tables. You then still face the prospect of ripping your home pc apart to put all this gear together and actually doing the conversion. Oh, and you've then got to dispose of the gear after.
You could go the second-hand route - a decent Pro-ject or Rega turntable for £80- £150 and you might get a better cartridge in the deal, but you'll probably have to buy a phono pre-amp as most don't have them built in. Pricewise you're almost back to square one compared to a new t/t and who is to say that a second-hand t/t will be in good working order when it arrives. You might save £20 or so on a sound card, but the same risks apply. Is it worth it?
Wouldn't it be much simpler and probably far more cost effective to hand the albums over to someone for conversion?
I have a Linn turntable. The cartridge alone (Dynavetor 10x4) cost as must as a new project Debut III USB. I have a high-resolution USB sound card that I use for audio analysis when looking at room acoustics, and with easy and cheap transport from Parcel-2-go it isn't going to cost a fortune to ship your albums to me. Would you consider using someone to do the conversion work?