Prices may be rising on everything from groceries to health insurance, but some fun things are still free — or close to it. Here, we offer up a guide to a bundle of Maine experiences that are all $10 or less, including some that call for an investment of nothing but (a good) time. ART & MUSEUMS Portland Museum of Art 7 Congress Square, Portland. portlandmuseum.org. Admission is free all the time for anyone 21 and under to the state’s biggest art museum. Admission is also free to everyone from 4-8 p.m. on Fridays, as well as all day every...