@Matthew Richey
I took a good, hard second look at the area, the home, the comps, and I have to stand corrected. I'm with you...I think you are in the right range. Hats off to you for having 25K. But for whatever reason, this seller has big ideas for the price he wants. The spread between list and sale on your comps is much more narrow than the spread you are shooting for.
I love your idea of adding a unit, but watch out for zoning. Make sure the city permits a triplex at this site. It probably is, but good to check on.
The psychology of sellers is hard to predict. I've seen sellers in my market just hold on forever until someone gave them their asking price. But this guy seems to be in a hurry. If your financing is solid, with pre-approvals in place, that may buy you some price reduction. But the comps belie that the spread between asking and sale price is much narrower than a 25% spread you are going for. Hey, I hope you get it.
Concerning the 2% rule, what determines the 2% is your gross rents divided by the purchase price of the house. So if each unit rents for $1100.0, assuming you rent both, than this property at $260K is a .08%.
You are 22, you have 25K, and you have the guts to invest in real estate, so you are ahead of the pack. One thing to consider. In 2006, the owner purchased it for just 52K. He has a big capital gain coming. Find out if he owns multiple properties in the area. You can do this by looking up tax records, then cross reference his name to see if he owns any others.
Knowledge is power in negotiations. If this is his only rental, you know something about him. If he owns many, he may prefer an all cash offer because he intends to roll proceeds via 1031 exchange to another property. I bet its the former...the impatience is there. There are a lot of variables here still to consider, but you are off to a good start. Please post what happens.