I couldn't open your image. I don't know if the file size is probably too big.
Anyway, no yellow handwritten letters. I think that is unprofessional and some owners might find it insulting :)
In my experience I have always sent typewritten letters, either as a self mailer on a heavier cardstock, trifolded, or in an envelope with some catchy phrases on the envelope itself.
You can design and print them in your printer at home.
My take on this is: you are not a family member or a friend, therefore the homeowners know that you are an investor looking to purchase their home.
It is more important that you come through as you know what you are talking about, offer something they cannot resist (moving expenses paid, for example), and some great headline.
For example I had a letter that went out that said on the envelope "We don't want your Listing!" and the letter went on explaining that I would buy the property cash, no marketing and wasted time on unqualified showings, etc (of course I had a clause in the contract about showing the property to qualified partners) and I would pay for their moving expenses up to $1,500. Great response!
Regardless of the size of the geographical area that you are targeting, test it by sending it to 100 owners. You should get 2 to 5% response rate, if you have a great mailer (that is what I shoot for.)
If not, tweak it, and send it to another 100 owners.
You will get a response, just try to maximize the percentage rate. :)