The cost is roughly as follows, based on where you raise the money from:
1. Angel investor, if you give them equity, that is a piece of your company - the cost is around $10,000
2. Angel investor, if you give them a convertible note, that is a loan - around $1,000 -$2,000
3. Angel investor, if you give them a Safe (Y Combinator alternative to convertible note) - the cost is either $0 if you use their agreement straight up, or a couple hundred to minimally tailor it