Those tape things do NOT sound awful. You must have bought a bad one or something!!!
As long as your tape player is okay and aligned, they can sound much better. I mean, it all depends on the quality of your speakers.
The only problem with the thompson one is that it might be difficult to use while driving.
Honestly, buy a tape thingy first! Buy a good one, and try it before you import some expensive fm thingy (aren't they illegal in Blighty anyway???). Then if you can't bear the sound waste your money on something else.
Having owned a lot of MP3 players, I would honestly say that Ipod DO make the best ones. (again I've never owned an I-River.) But the only ones I use now are my Ipod and my Ipod Shuffle. I will buy an ipod nano. And you can bung ANYTHING onto an ipod, in fact you can bung anything on anything.
But don't waste money on something you don't need....