I'm lucky to be a trailering boater so I'll be paying about $4.30 a gallon at the Hess station in town. All the guys I know in my club who have moorings and can't trailer because of the size go to Connecticut for gas. They plan Sunday brunch runs around fill ups. It's worth it when you take on 150+ gallons at a clip. I wish I had some valuable info for the thread, sorry. I have seen gas on land as cheap as $4.15 (Valero) and as expensive as $4.35 (Exxon/Mobil.)
Running tanks dry vs. keeping them full is as bad an argument to get into these days as it is to talk props with different mechanics. Ethanol is a solvent. It will make your tanks squeaky clean so yes running them empty as often as possible and letting quality filters do their job is a good thing IMO. The bottom line with ethanol in the gas during the season is you have to use your boat. At the very least you have to run your boat once a week minimum especially if it has carburetors. Give it a good 15-20 minute run at idle, or better yet take it for a quick run around if you're moored someplace. Gas stabilizers should be used year round. During the season a lot of guys in my club use the blue bottles of Startron. The stuff works great. Over the winter Stabil is a better option.
As far as winterizing goes, ethanol is at least 10% mix here, usually a bit more. So do the math for every 100 gallons of gas if you get phase separation or water in your tank, you'll end up with 10 gallons of bad ethanol and gunk on the bottom of your tank. I use the Racor fuel filters with the plastic bowl on the bottom of the filter. This lets me see what is in the gas and if bubbles appear I know I have ethanol phased out. It is up to you would you rather winterize with over 100 gallons of gas and potentially have to pump out 20 gallons or so or leave 50 gallons and only have to pump 5-10?