If you want a cheap rifle to get you started that you can customize later on to build a nice shooter out of, go buy a Remington 700 ADL 7mmRM from Academy Sports for $379.99, or buy a 700 SPS, or 700 Long Range in 7mm RemMag.
Stay away from the Remington 710/770/783 rifles. They are not upgradeable later on. There is no aftermarket for them. And there are no custom parts to upgrade them, if they're even upgradeable at all.
Do yourself a favor and buy a true 700 action rifle, like an ADL, BDL, CDL, SPS, Long Range, Sendero, 5R Milspec, etc... And not one of the econo 700-imitation rifles that are junk (710/770/783).