And I think the other's formulas about how to work out a price could be a little on the low side. Basic commercial markup is 110%. A supermarket buys a product for $1.00 and sells it for $2.10.
Most formulas, like those shared earlier, are were intended to provide a potential baseline "wholesale price."
As noted, one would then add a retail margin on that, if their intent is to sell them (rather than being strictly hobbyist e.g. proverbial elderly lady who knits for fun while watching TV, has hundreds of items and is primarily concerned with cost recovery). I suggested 30-50%, and I should clarify that this would be as a percentage of the final retail price. This basically reflects that when selling on consignment, especially at smaller stores, and for less expensive items that 30-50% represents a common "cut" percentage.
If we go with 50%, then the markup would be 100% from wholesale.
To put that into an real example, $40 wholesale / $80 retail.
The markup also allows the artist some wiggle room - there's always going to be people who want a discount, and I'm generally willing to offer 10% off to those who ask nicely. You also want to consider a multiples discount, typically for buying three or more (note how fast food usually has a main/side/drink combo), though if you are also selling through stores and other venues, you may not wish to advertise this (e.g. only available if asked for) as you do not want to be seen as competing against the stores/galleries that are carrying your items.
That brings me to my next topic - that one should ideally have a variety of price points. For "flat art" (paintings, sketches, drawings) - it's pretty straight forward - you have an original and prints on the more expensive side, and for those who wish to support you but aren't in the market for a full piece, you can also have postcards and greeting cards at the $5-10 range and depending on your genre, perhaps stickers and buttons at the $2-3 range.
With the smaller items, you'd almost always want to have a quantity discount to encourage purchases of multiples:
e.g. Postcards
$5 each, $20 for 5 (A 5-combo is desirable and is a common alterate to the standard 3-combo e.g. $12 for 3. Note that 4-combo is generally not used)
The great thing about e-commerce and made-to-order is that one can also offer things like t-shirts for $25.
Now,
@Rodafina, in your case, since you're selling 3D art, from a business perspective, I would recommend pursuing a different angle for alternative price points: miniatures.
If say, you decide upon $80 retail for a full-sized piece, I'd suggest $50-60 retail for a miniature. The idea is, as with above, to allow those who like and appreciate your art to buy a piece at a price that may be more affordable for them. But note that I am pricing the miniature at more than half of the full sized piece. This is because in your case, where you really have one flagship product, you want the focus to be on that, and you don't want the miniatures to cannibalize those sales. By pricing it somewhat close, relatively speaking, to the full sized piece, you can also help reinforce the sales pitch for the full sized piece. Someone thinking about paying $60 for the miniature will likely say "might as well pay the extra $20 for the full sized one."
To add to
@Outdated's other point, someone often neglected is the packaging and presentation. When someone gets it in the mail, the package should stand out and they should feel, when opening it, that it's something special and valuable. A personalized and signed thank you note (preferably one you've designed yourself), tissue paper, box or bag are simple things that go a long way. And this extends to the mailing envelope or box as well. A sticker that is connected to your product/brand would raise excitement when they get it. Hey, it's that (item) I've been looking forward to!
By the way, for anyone reading this, feel free to PM me if you'd ever like to bounce ideas on selling art.