You're going to end up spending at least $700 to get 50-60mph top speed with 25mins. of runtime. A more realistic goal would be 45mph and 15-20mins. runtime. If you plan on racing at a track, there's really no need for more than 45mph.
Here's just about the least expensive setup that you could do:
Wanderer 8XL motor:
http://www.rc-monster.com/proddetail...WAND_XL&cat=20
BK Warrior 9920 ESC:
http://www.rc-monster.com/proddetail...od=9920warrior
This setup would get you moving, but may have some problems with heating up too much. I personally wouldn't get the Warrior 9920, I've had to have two serviced and neither received much use, and it took 10 months total for BK Electronics to get them back to me.
A much better, but more expensive setup would be this:
Lehner 1930 11t motor:
http://www.rc-monster.com/proddetail...LMT1930&cat=20
Quark Monster Pro 125amp ESC:
http://www.rc-monster.com/proddetail...RK_125A&cat=21
This setup should run cooler, give more power, and will give better run time because it's more efficient.
For both of these setups you could use two Maxamps 2s 6000mah packs:
http://www.rc-monster.com/proddetail...S2P6000&cat=18 ($160, should give about 20mins runtime)
or two Maxamps 2s 8000mah packs:
http://www.rc-monster.com/proddetail...S2P8000&cat=18 ($210 total, but more powerful, should give about 25mins runtime).