if you just want bog standard goldfish you should be able to get them for about 99p. Garden centres may be cheaper than pet shops for the plain old ones. If you want something slightly fancier, say fan tails or different colours etc still should be only a couple of quid if they are young ones. You can get basic plastic fish bowls from Wilkinsons for about �5 (would only fit 1 or 2 small fish in though). If you want a glass tank of better quality they will be about �13-15 and up (from pet shop). Still probably can only fit 2 or 3 fish in the smallest ones without causing health probs. With the rectangular glass tanks you can fit a little filter to keep the water cleaner (less cleaning for a bit more money - its a trade off), filters are �15+. cost of gravel and a couple of plastic plants, probably a couple of quid each. Bargain! Some pet shops sell 'all-in-one' kits which give you everything but the fish (and water!), i think these start at around �20 with a not too small plastic tank and might be a better deal.