What a painting is worth is hard to say, probably hardest for the one who made it. But, if an artist is going to sell their work, then they're going to have to price it - no one will buy something until they know the price.
The prices you'll find on my website reflect my honest effort to place my work within the market around me. I've looked at the work of other artists in the area and I've tried to judge my own work against theirs, in terms of the technical execution, the creativity, and the experience I have as an artist. Too, there are people I trust who've looked at my work, who are artists themselves, and their feedback has helped me. I've also taken into consideration the cost of materials and work space. I use high quality oil paints and linen canvases - I wouldn't be happy offering my work made from "hobby" or "student" grade stuff. I've thought about what else someone's money can buy. For example, $500 may seem like a lot of money for one painting, but when a one day trip to Disneyworld's Magic Kingdom for a family of three could easily cost that much, it's not really. Or you buy a print of some famous artwork (and a print is nothing but a photocopy really), get it nicely framed and that would set you back a couple hundred at least.
Compared to what else you could do, original artwork is actually a great way to spend your hard earned money. A quality piece of handmade original art will easily last more than a lifetime.
If a painting is something you love, you should buy it, if not from me, then from some other artist whose work you appreciate.