I think you're taking a wrong approach.
Try the bike. If you like it get it. If you don't like it - then the price doesn't matter.
You can always get a bike that you don't like for $200 in Walmart.
and don't go by some chart that says you need such and such. you should either try the bike or do a professional bike fitting - preferably both
the apparent $aving$ can be an illusion anyway. for example i thought i was saving tons of $$$ when i paid $999 for a $1,999 Giant. Turned out i got a 3 year old model, with previous generation components. i think i still got a good deal but the saving wasn't so great that it should have affected my decision as much as it did. i was going to get a Specialized but got a Giant at the last second because of the sale. i was so eager to get the Giant that i didn't take the time to ride it and see if i liked it - turned out that the seat it came with was painful. i eventually had to replace it with a Specialized seat similar to the one the Specialized bike i wanted came with stock.
if i was doing it over again i would take more time making sure i am getting the right bike, and less time worrying about saving a few pennies.
moving the seat front and back to compensate for frame size will alter the angle between your back and legs. this will have a big effect on the way you produce power.
i am not going to buy another bike without doing the fitting first. charts are useless. a chart put me on 130 - 143 mm seat. the seat that actually fit my butt was 155 mm. it had tried sitting on 5 different seats before i got one that fit me. and that's how i will be shopping for my next bike.