The revo is $504 at tower hobbies and it only has the 3.3 engine.
http://www2.towerhobbies.com/cgi-bin...I=LXMHP1**&P=0
The savage is 4.1 (rtr) and is $439.
http://www2.towerhobbies.com/cgi-bin...&I=LXMCA1&P=ML

I'd go with the savage its cheeper and has a more powerful engine. It will be cheeper to buy the one with the more powerful engine to begin with, than to cheep out and upgrade later. ($150 - $200)

If you have the money, the savage is also avalable in 4.6,
http://www2.towerhobbies.com/cgi-bin...&I=LXMYA2&P=ML
its $20 cheeper but doesn't come with a radio, so buying a radio will cost you around $100

I would get a three channel so in the future you can get the reverse modual
http://www2.towerhobbies.com/cgi-bin...I=LXCHA7**&P=0
http://www2.towerhobbies.com/cgi-bin...I=LXGAG4**&P=0