before was 5 or 10 baht for regular Thai post. Take about 1 month. Now they charge 40 or 50 for express delivery. Around 1 week. If my memory is correct.
it’s not a 7 days visa. It doesn’t look good to have a 7 days denied stamp in your passport. If you really need more than 75 days but under 90 days. Just do a border run at the end of your 45 days visa exempt. That way you will have close to 90 days in Thailand. Without any bad record in your passport.
I had my visa and TM30 in Chiang Mai. I bought a car in BKK, during the transfer book to my name. I was near Sriracha. So I did my COR at sriracha immigration office. I give my hotel address at sriracha. No problem at all. All done in 20 minutes. I got my book after 1 month by mail. All immigration office might have their own rules. This just my experience at Sriracha immigration office.
if you don’t want to pay those fees. But to have a visa and WP. You might looking for a job which can supply you a working visa and WP. Also making money from your job too.