or two domains point to the same site, and have a $20 in the logo slashed out, replaced with $15.You're the creative one - make it work :)

This would make for a fun A/B test: "$15 + $5 extra" vs. "$20 - $5 discount".

You might collect some evidence that people like getting a deal more than getting hit with an extra cost.

to get a design for <$30, your not going to notice a huge difference in acquisition for the $5

Probably, yes, but hard results from testing FTW.

  it'd require changing of the domain name.

So? He only started yesterday. If the domain isn't already taken then what's the big deal... it's not like he's spent a lot of money advertising it. :)