I would enthusiastically recommend Sally's generic version of Joico K-Pak Reconstructor. Excellent protein DT, smells good, only $5. What's not to like? (You know to use a moisturizing condish after a protein DT, right?)

Another inexpensive one that turns up in beauty supply stores is Hy-Pro-Pak. I have not actually used this one but I've seen good review, and it usually runs about $4.

If your budget can go to $8, the DT from the Activate line is a nice one too.

These are all without cones.