If you're lacking a towel (see: TOWELS), you probably want to rectify this condition, and there's no better place to get a first-quality towel than ArthurDent's Galactic Bazaar. His towels are the finest available on TinyTIM, passing all of the seventeen trillion strenuous HHGTTT Towel-Testing Tests which we've devised over a period of years, and the AD brand towel even comes with bonus fruit flavorings for when you're tired of vitamin C. (Sorry, antidepressants are not available at this time.)
Not only that, the hungry hitchhiker can obtain provisions for him/her/itself. Cheap. Try the Perfectly Normal Beast at Stavro Mueller's Gamma...it's absolutely incredible.
SHOPPING: Towels, 100 pennies. PNB on Rye, 20 pennies. (Worth each and every one.)