Accommodations under $250-300/night are tough to come by on Nantucket, so I was delighted to find Roberts House Inn, where the most expensive room is $150/night, after some serious research online. The room wasn't luxe by any stretch, but met/exceeded my expectations for what we paid. The room furnishing and en suite bath were on the older side of things, but well kept and clean. I wouldn't count on the continental breakfast for your morning meal, however. The coffee was good, as were some of the pastries, but the selection was otherwise lean.
If you're okay with basic accommodation in the heart of Nantucket Town, I'd recommend Roberts House.
