Neither the GTX 680 nor the GTX 770 cards are "budget" graphics cards, in terms of low cost - both of those graphics cards are in the high end (money & performance). The GT640 is the budget card in the tonymacx86 Buyer's Guide. I use the GTX 650 Ti with very good results. The GTX 650 Ti Boost is also a good graphics card. The rest of the cards are for there for gamers.
Note: as of the time/date of this post, this is the current Buyer's Guide graphics card list:
http://www.tonymacx86.com/398-building-customac-buyer-s-guide-november-2013.html#gfx_cards
I would try your development activities without a graphics card at first. The HD4600 Intel Integrated Graphics is surprising powerful (in terms of graphics in the past 3-5 years ago). See the
Tom's Hardware Graphics Hierachcy Chart for more information.