As any weary traveller should know, there's no such thing as a free lunch. But if you look hard enough, you can always find a cheap one. Pay-what-you-want restaurants offer their customers the chance to fill up without obliging them to empty their wallet when they're finished. Of course, that doesn't mean you should take advantage, but it's always good to know there's a place where you can eat out without getting a shock when you see the bill at the end of the evening. Here's a round-up of pay-what-you-want restaurants around the world, where you can find highbrow grub at low-end prices.

Lentil As Anything, Melbourne

First founded in 2000 by restauranteur, TED talker and tent-residing "social challenger" Shanaka Fernando, there are now four branches of the ambitious "pay-as-you-feel" eatery in Melbourne. The vegetarian restaurant is founded on a manifesto that aims to promote community values and counteract the feelings of division and inequality caused by money. The taxman, however, has been less than impressed. But in 2007, the not-for-profit organisation won its four-year battle with the Australian tax office to be exempt from goods and service tax (the Australian version of VAT). The Abbotsford Convent branch, with its leafy garden seating, is the biggest venue, feeding 900 happy customers a day. Just pop your anonymous donation in a wooden box on the counter when you're full.
• 1-3 St Heliers Street, Abbotsford, +61 3 9419 6444, lentilasanything.com. Open daily 9am-9pm

Pay As You Please, Killarney, County Kerry

Located in the bustling tourist town of Killarney, south-west Ireland, Pay As You Please is a popular cafe serving a range of "soul food" - pizzas, salads, soups and buschette - rustled up by a chef trained at Darina Allen's famous Ballymaloe cookery school. The chilled-out eatery fills an old warehouse, which also screens black-and-white films projected onto the wall. As well as being able to pay what you think the meal is worth, guests are welcome to bring their own booze, making it the ultimate in budget dining.
• New Market Lane, High Street, +353 87 190 2567, facebook.com/payasyouplease. Open Wed-Sat 12.30pm-10pm, Sun 12pm-4pm

SAME Cafe, Denver, Colorado

Denver is a pretty chilled-out town. No surprise then that it boasts not one, but two pay-what-you-like restaurants. SAME is the oldest of its kind in the city, opening in 2006 after being inspired by the trendsetting One World Cafe in Salt Lake City, and serves fresh, healthy dishes such as kinawa soup and panzanella salad. Denver's other "free" eatery is Cafe 180, which lets guests volunteer to earn their meal.
• 2023 E. Colfax Avenue, +1 720 530 6853, soallmayeat.org. Open Mon-Sat 11am-2pm

Soul Kitchen, Red Bank, New Jersey

The JBJ Soul Foundations's community restaurant (in case you were wondering, the JBJ stands for Jon Bon Jovi) serves up a three-course meal based on regional cuisine and local ingredients, some of which are grown in their own organic garden. When it comes to the bill, guests can either pay a minimum donation of $10, or volunteer to help out at the restaurant.
• 207 Monmouth Street, +1 732 842 0900, jbjsoulkitchen.org. Open Thurs-Sat, seatings from 5pm-7pm, Sun seatings from 12pm-4pm

Der Wiener Deewan, Vienna

This hip Pakistani food joint in Vienna serves up a delicious curry buffet in a small brick cellar that fits around 50 diners. It's an all-you-can-eat, pay-what-you-can bonanza. For the real Deewan experience, drop by on one of their "play-as-you-wish" jam sessions, where you can take advantage of their BYOD policy. In case you were wondering, the D stands for djembe.
• Liechtensteinstrasse 10, +43 1 925 1185, deewan.at. Open Mon–Sat 11am-11pm

De Culinaire Werkplaats, Amsterdam

Unlike the hearty fare usually found in pay-what-you-like restaurants, De Culinaire Werikplaats takes a creative approach, putting together vibrant recipes inspired by regularly changing concepts such as "honesty", "flowers", or "black". The menu only hints at the dishes - telling you the ingredients, but not revealing the finished product - but expect a very classy experience indeed. Another Amsterdam eatery worthy of a mention is De Peper, inside the OT301 venue - a former squat on the Overtoom, one of the city's main drags. They serve up big plates of vegan grub and diners can pay on a sliding scale according to their budget, from around €7-10.
• Fannius scholtenstraat 10, +31 65 464 6576, deculinairewerkplaats.nl. Open Fri-Sat 6.30pm–10pm, groups of 15 or more can book outside opening hours by appointment