Dont think the price I paid will help you much as it was done between the master cover designer and myself and was a "very" good price while establishing exactly how best to do it. My rationale was that the boat was on davits and UV would probably half its life. Any less than half the cost of the dinghy would be a bonus. It also makes it easier to clean (washing machine) and if you can see on mine, there is a wide webbing strap all round the outside acting as a buffer when rubbing against walls, etc - so I would expect it to be less vulnerable to punctures as well.
Have made a cover for our new excell inflatable, however we also made a cover for the air deck floor as well. In addition we have a spray dodger, 2 purposes (1) to protect shopping etc. (2) for ziggy, the mousehound, to stand on. All designed & made on our Moody. A plastic pattern, using 2nd hand plastic from a newly delivered boat. Saloon table for cutting (carefully) and an old 57yr old singer machine. Hopefully I'll be able to post a photo or 2 when I read the distructions tomorrow! I always have 20 odd metres of canvas on board, get withdrawal symptons otherwise. I order canvas from Kayospruce (hope it's okay to mention the name?) Realistacally it took 3 working days, but as I'm out of practice it was over a 10 day period. It is not too difficult a task if you have a good 'technical manager' (my husband) who was very good at calming my panic attacks when trying to work out how to attach the canvas to the pointy bits of the sponsons.
Difficult to estimate costs but will try and do a 'costing' along with the photos. Would not recommend using a washing machine to clean the cover. Scrub gently with a non detergent and rinse. A sacrifical strip around vulnerable areas is an excellent idea. We have a double strip of webbing around the whole dinghy plus the spray dodger which is a heavy duty w/proof canvas.