Negoiating with overpriced listing

[Chris M.]

I'm interested in purchasing a 3 bedroom co-op that was listed for sale 6 weeks ago.  It's listed at 299k, but after running comps its value is around 250k.  It needs to be gut renovated.  

I offered 240k cash, and listed comps explaining the offer but the selling agent doesn't to be very good and doesn't want to listen to me.  She hasn't even posted pics on the listing.  

Should I just wait a few months and try giving the same offer again?