It is difficult to give an estimate of cost. You may want to include a photo with your query and a little more history. Also, you may want to consider a hair transplant to lower the frontal hairline.
Typical side effects of using Minoxidil include dry itchy scalp, flakiness, burning irritation. Be sure to read the directions and do not use too much to avoid systemic absorption as this can lower blood pressure and you may experience vasodilation and headaches.
Yes minoxidil can cause weight to increase. Absolutely. However, you need to see a good doctor to answer this question fully. Minoxidil can cause edema (fluid retention) and for some, yes it can cause weight gain. It’s fluid not fat. See an expert.