There are a lot of good, inexpensive broad heads out there. Zwickeys will probably be the most economical for you.
You didn't say if you are nocking above or below the arrow. I'd suggest, if you already aren't, using two nock sets, one below and one above the arrow. Leave a small (1/16") gap so that your arrow isn't pinched at full draw. Two nock sets will prevent your arrow from sliding on the string, which will screw with your tuning.
In regards to nock height, it needs to be what it needs to be. I usually start with the lower nock at 3/8" above parallel and adjust from there. Make sure you don't go too low, or you can get some screwy results. The shaft will bounce off the shelf and give you a false low reading.