Hi,
A friend of mine recently purchased the RioSport
S30S , a 64MB player, retails $149. She loves it.
There is also now the RioSport
S35S , a 128MB player for $199.
I've not personally used either. But, they both meet your requirements. (flash media based, FM radio, gym/sport oriented, iTuens compatable, etc.) A few reviews state poor FM reception, so you might want to check that out before you buy, as they are available at several electronic chains. There are other players with FM, but I don't know about the iTunes compatible. FWIW, I'd avoid players that required third party 'music managment' software, none of them compare with the ease of iTunes.
Good luck in your search