Fees to charge for making spheres from provided material

I usually go to a rock site and see what prices they are charging, than just equal it out..

Another thought. When I have people ask me to make spheres for them, I tell them to preform the sphere so that it will easily roll on a table. I never had a person deliver a preform. LOL

I’d say the first question to ask is do you want to do this?
Second: who’s asking? Friends that you like? Would it be enjoyable enough just to cover your costs, or is people you don’t know/like that well, but who are hoping you’ll do it cheaply?

I suspect that anybody who asks you to make a sphere has no real concept of the work involved. The Saw time alone it daunting. And not just the cutting, the setting up the cuts. At one time I thought about making a few just to do it. I backed off once I understood the work and time required. I had much better ways to spend my time.

Sometimes they break during rough grind. I've had chunks come out as well. I fill every crack with thin superglue and cross your fingers.

How many hours would you have into a 3.5"  agate sphere with cubing, preforming, pre-grinding and actual time on a sphere machine?

I am asked that question very often. If I was to only work on one sphere and do nothing else I would guess 20-24 hours. When I am in the shop I try to do as many things at the same time as possible. I usually have two 18" saws going, my old but trusty sphere machine going, I also run a high speed sphere machine and I try to get on the wheel to grind the preform. Once I adapt my shop a bit more I hope to have my 30" saw running more often. So now I can have up to 5 or 6 tasks going at once. Does this cut the initital time estimat down? Not really. But it allows me to continue to do this without regret that I am only making a couple dollars an hour. Also, I try to line up a good number of similar size spheres so my polishing is more efficient as well. Less time changing cups.

I have made exactly one sphere. I went to a guys house and he walked me through his process. It took 2 days for 1 sphere. Rough on grinding wheel then finish on a home made single cup setup. I have not had the time to make them when they can be purchased so cheaply. That said special rough that is/has sentimental value you must put a $$ figure on it if you are interested in the business. That price helps the customer determine if it is worth it or not. Figure out how much you want to make an hour and figure the hours it will take and they can take it or leave it. that will help you weed out the lookie-loos vs real customers. Of course I have taken jobs I tried for $30 per hour and ended up at $2 per hour and some jobs are just interesting enough to make you want to do them at any price.