opengate has it in stock if you're looking for diy websites. You can also get it from a lot of grey market pharmacies (can link a handful if you want), but make sure you're getting bio identical progesterone and not medroxyprogesterone. In my quick research I see a few trans women talking about taking the depo shot and liking it but I haven't researched that option at all. Its not bio identical afaik and generally that's what I'd recommend.

Cost is a bit more then E, from opengate (looks like they may not ship prog globally, look at other diy sites ig) they have 60 200mg for $100, this pharmacy I'm looking at rn has them 10 for $10 (or 100mg 10 for $6.5). Taken daily that's like $350~ a year. To be totally clear I personally haven't ordered off them before but I know people who have.

You can also make your own topical prog, I unfortunately don't have a guide handy atm I can try and find one if you want though. Although I have heard diy topical is not good for long term use, but iirc a couple of years is fine.

Also, sorry for the long info dump, you might want to wait a bit longer? Usually the recommendation I've seen is tanner 3. Prog helps breasts switch from growing out to filling them in, so starting at one year is not always best. Up to you ofc, I don't have a ton of research in front of me to link, but do your own research and decide. There's not really any consequence afaik to starting and then stopping later if you decided you did start too early. But yea, tanner 3 is a more important milestone then year 1 imo. Hope some of this was able to help. Feel free to DM or tag me in the next mega if you have questions or anything.