Sanity check needed:
Item on sale for £30 - buy it now or best offer
Offered £23 - rejected
Offered £26 - also rejected
Offered £29 - awaiting decision.... (fully expect it will be declined) 
I find this most odd - WTF would you bother listing an item with 'make offer' if you are not (apparently willing) to accept what seems a reasonable offer?
When I am selling in this format, I usually accept anything around the 75% mark. Maybe I am just too generous with offer acceptance.....?
Ho hum... as you were.