Kotupod
Ill second the recommendation for a Ruger M77 or M77 MKII, but only because Im an unabashed Ruger fan every one I have is a good shooter.
However, Ill also second the idea of purchasing a used rifle. Three of the centerfire rifles in my safe were purchased new but six were previously owned. No one could tell the difference either in the way they look or the way they shoot, but I saved a bundle on the used ones. In the case of the Ruger .257 Roberts it was an older (1989) M77 with the tang safety and a Leupold M8 4x scope mounted. It had been shot so little there were no marks in the bluing under the tang safety, something I corrected the first week I had it. The rifle and scope cost me an even $400. A few days ago I picked up a 1975 Remington BDL in excellent condition for $330, caliber .308 Win. The money I saved on the rifle will go toward good glass. Not every used rifle is a bargain but there are still a lot of excellent deals out there if youre patient and willing to look around a little.
As to caliber for whitetail, anything from a .243 Win and up will work. (A lot of people like centerfire .22s for deer but they are not legal where I live and I wouldnt use them if they were.) If it were me Id be looking at .25-06, .260 Remington, .270 Win, 7mm-08, .280 Remington, .308 Winchester, or .30-06. Id avoid bullets lighter than 100 grains in the smaller calibers and when muzzle velocities exceeded 2900fps Id want premium bullets that would hold together a Nosler Partition would be fine. Id avoid the magnums - whether short regular or extra long and Id avoid odd-ball or hard-to-find cartridges, cartridges that have a poor selection available, and cartridges that cost a premium. If I was on a budget I would strongly consider the .308 and .30-06 because of all the inexpensive ammo available for them my goal is to shoot, not to empty the pocketbook.
If varminting was a potential use for the rifle I would lean toward the .25-06. If not I would lean toward the .308 Win.
For a scope I would also consider used. Four of my five Leupolds were picked up used at gun shows, three for only $100 each. The Leupold VX-III 4.5-14 that now rides atop my .257 Roberts was picked up used for $350 and is easily the best glass I own. In new glass I would consider the Simmons Aetec for about $110-150 depending on the configuration (my hunting buddy and I both have one on our 7mm Mags and are very happy with them), or a Burris Fullfield II Ballistic Plex for about $180. I have one of those on my .300 Win Mag and will probably pick up one for my new .308 Win the graduated range reticle is perfect for my particular needs. When I got my first centerfire rifle back in 81 I put a new $40 Bushnell Sportview scope on it. The scope was never very good in low light situations and I was never very happy with it, but it helped me take a lot of game and it survived a lot of abuse, including an accident that cost me two broken ribs when I landed on top of it. I was on a very limited budget at the time and that little incident made me very happy I didnt have an expensive scope. Nowadays I prefer better quality glass but with two kids in college Im still on a budget. Buying used scopes allows me to get better quality glass than I could if I were to buy new.