With that budget, I'd buy the SP14 and PH16 kits from VTA. Talk to them about building the SP14 with balanced outs if you like. Not all that hard to build and a major ton of satisfaction you can't get from any standard commercial preamp at any price. AND the quality will be every bit the equal or better than anything else mentioned here. Check 'em out at:
http://tubes4hifi.com/
http://tubes4hifi.com/