>>>fenlander will be along shortly he has a wealth on knowledge on sib repairs.
Well only recently acquired in truth... and from advice on here... but it was a baptism of fire and taught me loads so I have no fear of making repairs now.
I'd just wonder if you want a SIB to use or fancy a project? I've seen (and sold myself) old Hypalon SIBs in the 3.1-3.5m range for that price that were ready to use with no repairs needed and immaculate.
Look at this which made less than £200... zodiac 4 man inflatable | eBay
And this which made less than £100... C- Craft inflatable boat. not zodiac, avon | eBay
Personally if I was looking at the one in your image... and I had reason to want such a thing...I'd offer £100 and see what reaction that got... and only then as long as it was holding air and there was no transom rot.