First of these is a bell. Now, I've chosen this not just because of its price, but I also like the no nonsense style of it. Some bells look a bit toyish, suitable for kids' tricycles and maybe unappealing to adults, this isn't. It looks quite businesslike, gives a single "ding" audible from quite a distance, and costs 99p from Wilkinson's. You can even buy the same thing from some other stores for £4.99...
Second is this cupholder I recently bought from Tiger - a chain of cheap novelty stores based in Denmark and established in the UK, with round prices - this was £2. Keeps my beverages close to hand. Seems to work OK - just fitted it and works fine - stayed put and provided the ground's not too uneven, the liquid doesn't spill...
Third, the Lidl bike maintenance stand at £30 - bit of a star product this...
Visit UK cycling forums and, chances are, you will see threads on this bargain of bargains. In short it costs £30, a third of the price of anything that comes close, has its own tool tray with a magnet for screws etc, (on others this is an extra to be purchased separately), is sturdy with a 30kg weight limit (many don't exceed 19kg, whilst town bikes can weigh over 20) and comes with a 3 year guarantee.
Lidl supermarkets (from Germany) have themed "weeks" once a year on different types of products/interests; during "cycling week" (around August/September if I remember correctly) - first come first served - these workstands go on sale (along with other cycling stuff) - and they're popular: advised to get there early, I got to the local Lidl just after 8am on the first day of "cycling week", when it opens, and about 10 people had already bought theirs before me...
To be fair, and going back to the getting what you pay for thing, this workstand is not the same as some of the more sophisticated stands from Park for example (costing over £250). It holds the bike by the bike's centre of gravity and you cannot position it exactly through 360 degrees. But as a starter for the DIYer, it doesn't get any better than this.
British cyclists can be a thrifty lot, so you can find out quite a bit about bargains from their forums. Lidl's is a favourite with lots of well made useful inexpensive stuff all with a 3 year guarantee. And no, I don't work for them! Another is their direct competitor, Aldi whom I've never been to (or at least I cannot remember).
Some links to start bargain hunting from: