Can anyone tell me the general difference in selling price there would be if I sold an uncoded template (wordpress), or coded and then sold it? I'm trying to decide whether it's worth it to spend the time coding it...
I would say that you could increase the overall price of it by 100%. I think most people consider the design and the coding to be about the same workload. So if you were going to sell it for $20.00 uncoded, you might be able to sell it for $40.00 coded.
It's hard to set a specific value since it varies from the original design's cost and the code's complexity and time. I don't usually charge over 80$-100$, a bit more if they need a CMS integration.
I would say, spend the time to code it. I have seen some arguments here on DP about people buying uncoded themes, and then having a fit because it's not coded. Just know it's something you may have to deal with by selling design only.