I own both the Grado SR225 and the SR80. They are *very*, *very* similar in sound. The SR225 is a bit more 'refined' than the SR80, but they sound very much alike. Really, they do. I can only hear a difference if I really am looking for it.
If you liked the SR225 but cannot afford it, I think the SR80 is the choice for you. It offers 99% of the sound of the SR225's at half the cost.
I say pull the trigger on the SR80's. If for whatever reason you don't like them, they, like all Grados, hold their value quite well, and you will lose little to no money selling them here.
Just my $0.02.
PS - If you are interested in purchasing a very lightly used SR80, PM me! I am going to be putting my SR80's up for sale very soon. What I said above (my suggestion for you to try the SR80) is in no way affected by the fact that I am selling mine; I truly think that they are the best choice for your particular needs.