Hi Jerry,
I think you're going to love your tablet once you get it. The greatest benefit for me is that I have much greater control over the position of the cursor when doing intricate selections, etc. For Photoart Painting, I think you'll be amazed at the control you have over the brushes. You can set the pressure sensitivity to control the size or the flow of the "paint" in the new PS7 brush engine. (Not sure about earlier versions.) Just don't forget to use the setup utility that comes with the pen so that you can set the pressure levels, etc. to your liking. (And make sure that you set it to "pen mode" rather than mouse mode when you're using the pen. I know someone who got a tablet and just hated it! Turns out, she had the driver in mouse mode and was using the pen - once I tried her tablet I knew exactly what the problem was. No wonder she hated it!

)
Also, not sure what size you're thinking of getting, but if you get a larger one and find that you don't like moving your arm so much for day-to-day tasks, you can tell the driver to map just a portion of the tablet to the screen. I use my pen exclusively (never use the mouse that came with my tablet) - for everything I do on my computer. I like it that much!
In terms of mail order places, I've become intimately familiar with all of the price comparison sites over the past couple of weeks. Most of the price comparison sites also have extensive user reviews of the stores, so you can compare prices as well as store ratings. It's hard to give the best store for prices, as it seems that it varies for each item you want to purchase. So, I've found it best to go to the price comparison sites, then get the best price you can after reading the user reviews of the stores. Be sure to actually read the reviews (the most recent are the most relevant) because sometimes what people are complaining about are something that I'm not concerned with or wouldn't apply to my situation. The star ratings are a good place to start, but be sure to read the reviews behind them.
That said, here's a bunch of price comparison sites:
Price Grabber Epinions BizRate DealTime - user reviews not as extensive as other sites
CNET - no user reviews
Price Scan - no user reviews
As for my own experiences, I've purchased from Mwave.com, newegg.com, buy.com, bhphoto.com and others which I can't remember off the top of my head. I've been happy with all of them. Buy.com sometimes has things which are not in stock - they will not charge your credit card until they ship and you can cancel your order prior to them shipping at any time. I did this when waiting for my scanner (it was backordered and the ETA kept getting pushed out.) I had no problem cancelling the order and nothing ever showed up on my credit card.
Also, don't forget to look at eBay. I buy lots of stuff there, but be sure that you know the cheapest price you can buy elsewhere so you don't end up paying too much. (I'm amazed at how much some people will pay for things on eBay!) Also, be sure to read the seller's feedback. And, I often send e-mail just to see how responsive the seller is (an indication of how communication will go after the auction has ended.) Gut feelings are also useful. There have been a couple auctions where everything looked good, but something still just didn't feel right to me, so I didn't bid.
Good luck!
Jeanie