I don't know which models you're interested in, but it looks like everyone's pretty much out of 590A1s with 18.5" barrels, though the best prices I see are around $450, delivered (model#50776). The 20" 590A1s are out there, but it looks like they're running about $50 more. As for 590s, I see the 7-shot (model#50778) for as little as $309, delivered.
The best way I've found to search gun prices is this website:
https://gun.deals/
Search on either the manufacturer's part#, or the UPC, and it's show you a list of several dozen online dealers, whether they have it in stock, their cash/credit prices, and shipping charges. The search engine can also be used to search for other firearm related items like parts, accessories, optics, etc. The site is legit. I've used it to find great deals for my last four firearms purchases.