I mean for the price at around .83 cents a letter and .48 cents a full color postcard I am going with them. 

Therefore, mailing a series of simple postcards that may be read by others is acceptable. 

If you have a site and are doing your own marketing to find leads via postcards, yellow letters, bandit signs, website etc.......then you really don't need the help of an agent.  

This will cover direct mailing costs, pre-foreclosures listings, bandit signs, postcards, etc.If you want to do fix and flip or buy and holds be prepaired to have 20-25% of the purchase price + repairs+holdings+etc. to come out of your pocket.

Will they merge your spreadsheet names and property addresses to each postcard?

Like what types of things do you actually say to the homeowners when you first approach them, what letters/post cards do you send out do you send out.

Some of the cheapest streams for marketing:1. craigslist2. facebook3. instagram4. linkedIn5. bandit signs6. car magnets7. parking lot - post cards8. emailing listing agents9. leaving post cards at laundromats10. door knocking NOD's (share this listing w/ a realtor - build relationship)11. guys - wear a  T- Shirt      "I BUY HOUSES" 12. introducing your self at open houses13.

A postcard is less than 1/2 the cost so you can send out WAY more for the same $.  

What exactly your post card or letter say?

Clean, newer, nice hood and schools types will offer real returns vs some old POS  duplex in a torn up part of town with no post card envy.