I think it would be real hard to find a MFA for that kind of money, they have gone up a bit in the last few years. You are probably looking at $1000+ now. There is one on eb right now for $400 but it needs repair. However preamps are not that complicated and probably $250-$300 in redoing and you'd have an excellent piece. .You can get a real nice Onkyo p308 in your price range and it’s a terrific pre amp
Sleeper preamps: $500 new/used
Looking for tube or solid state pre with very good phono stage...willing to go used and go with an older model if sound quality is superior...any models come to mind?