I would first research getting SMP in your home country. At $500 for the I'm sure some talented people in your home country will have spotted a gap in the market at a far cheaper price than abroad.
If you decide to go the DIY route you can patch test an area, live with it for a month or two and decide if you are happy with how it blends in.
Undoubtably there is real skill in blending in a SMP hairline (the internet is full of bad examples) but the donor areas would be less challenging.
You feel that the HT was a mistake so now is the time to breath, relax and take a measured approach and not to rush into a disaster. The fact that you are researching various options suggests you are on the right track.
The Aphorism: "Act In Haste, Repent At Leisure" (givemesomeenglish.com)