Avon 310 Air Floor or RIB ??
Thanks for the input .. it is an Avon 310
If it is a RIB, just go through the hull from the bottom with a bolt, a fat fender washer, an eye nut on the inside and a good amount of 5200 to seal (which is what Avon & Zodiac have done for a while).
If air floor, just buy two 151 stainless d-rings from Defender [or some other place] and some two-part Hypalon adhesive. Mark where you need them based on your davit arm spread, prep the fabric and adhere the d-rings. Really not hard.
Could be that the Dealer you are speaking to is quoting you on Avon's d-rings, which do cost a lot. You can go generic as long as they are robust. The bigger the surface area on the d-ring apron, the safer the boat will be.