I love the idea of the Soma Mixte for your needs, but I'm partial to Soma since I love my Double Cross dc so much. The Tange Prestige tubing they use is excellent. But, if you go that route, it might be hard to stay in budget, as I've found when building up a frame, it's not easy to choose lesser components to keep the price down. You can do it, but you'll probably have to make some compromises. I blew my budget on wheels.
In hindsight, I'm really happy I did. I sold my trainer to pay for them, and I haven't missed it for one second, even this snowy winter.
It looks like it comes in an extra small (size 42 cm) that takes 26" wheels. I'd be really surprised if that was too big for you, as I'm 5' 5 and ride the 48 cm DC.
ETA: I just noticed you have a bike you can take parts from. That could help!
Last edited by redrhodie; 02-04-2011 at 02:48 PM.
'02 Eddy Merckx Fuga, Selle An Atomica
'85 Eddy Merckx Professional, Selle An Atomica
'10 Soma Double Cross DC, Selle An Atomica
Slacker on wheels.