Two GTX 460s will be faster than a GTX 470 or 480 (thanks to Nvidia's great scaling in SLI), but that's the limit of their expandability. If you want more power in the future, the GTX 470s support 3-way SLI, and are more powerful than the 460s when comparing single cards.
I recommend EVGA because of their lifetime warranties (product codes ending in AR) and ther Step Up program that comes with the lifetime cards. I'm trading up my GTX 460s for 470s for only $35 per card (including shipping both ways), and plan on adding a third card after a PSU upgrade. They also offer external exhaust cooling on several models, which will help keep the rest of your components cool.
MSI also has a great card with their Cyclone (I was recommended that card when I bought mine), but EVGA's Step Up program was what won me over. Just something to keep in mind when choosing brands.
since im going to buy this next year around mid jan or early feb should i wait for the 470 prices to go down and but 2 or just go with the 460?
A lot is gonna change between now & Feb. So it makes pretty much no sense to have any rigid plans as to what you might wanna do then. Even if you were to buy now, your decision will depend on the games you play, your resolution & the settings you wanna play on. Ultra on 1920x1080/1920x1200/2560x1600 with DX11 @ 8XAA with tessellation and PhysX enabled will need a different beast from the basic 1280x1024/1366x768/1600x900 DX9 2xAA.
If you were to buy now, 2XGTX 460 will pretty much be the way to go even though I don't normally like dual GPU solutions to start off with - leaves little headroom for upgrades. Though the point is, with 2X460's (stock 1GB) you wont need to upgrade any time soon seeing as they trump not only the 480's but also the 580 - forget 'bout the 470.
Will be slightly more expensive though than a single 470, but well worth it if you can afford 'em.