And then buys a T-shirt with the city's name on it! 

At this point I would really suggest you think about what you want to do, make a detailed plan on how you want to do it and then research it so you arent the guys crying when you lose your shirt.

I love that REI offers the opportunity for reaching FI quicker due to leverage and rents, but I don’t want to lose my shirt, either.

You get into pre cancelled/pre sorted stamps and it's going to lower your response rate.

I almost spend that much on a stamp, #10 envelope, #9 envelope, and a piece of paper.  

I plan to mail to 100 at first.  49 cents a stamp.  

What's $5,000 in stamps, paper and envelopes if it finds you several deals worth $30,000 - $40,000 each?

I know a lot of guys who lost their shirts being over leveraged in 2008.

With odd sized hand stamped and addressed envelopes, I hit 21%. 

the bottom line is the more personal the mailing looks the better its chances of surviving the trash can.Things I have used include a live stamp... placed crooked on the envelope/post cards.Hand written addresses and returns as John mentions.Letters vs. post cards.