I do sell my work! Right now, most of my sales have been through eBay, or purchased from me directly by users on Reddit. I have two options for buying my stuff.
1) Purchase - This option is self explanatory. You straight up purchase a custom from me. The price covers the figure, the customization, and the custom box. Prices are determined by the rarity of the figure and the difficulty of the paint job. It also depends on if I have a spare of that character on hand/how easily obtainable it is for me.
2) Commissions - This is where you send your own figure to me for me to custom, and then I mail it back. Pricing is still relatively the same, but a little less since I don't have to provide the figures. Prices are still determined by rarity of figure, difficulty of paint job, etc.
I also do a sort of "in between" option. You would still provide me with a figure and payment for the work, but if I have that particular custom in stock, then we can pretty much do a swap. This way you don't have to wait for me to receive your figure and then take the time to paint it. It's basically the "purchase" option, but instead of paying straight up money, you mail me a figure and make payment and I pretty much mail the pre-customed figure immediately. In other words, this option gets you a figure a lot sooner.
There are a few other methods of payment and stuff, but I don't want to overwhelm you. I can tell you that the black coat Dr. Mario would be $15 + your figure + return shipping for a commission, or $30 to purchase directly. I do have Dr. Mario on hand (but not yet painted), so that could be done pretty much whenever you want if you're still interested.