Nowadays the cheapest ivybridge i5 is the i5-3350p, so you might want to check that cpu if you want an intel cpu, the 7870 is obviously better, if you can fit it with the i5 the better.
If not, you might take a look on the amd side with the FX-6300(not the 6200 which is from the older bulldozer architecture) and the 7870.
Another suggestion is to look for a 7870 tahiti le if the 7870 you had in mind is at the same price as of the 7870XT.