£30...
Do you want a single big gift or would several little ones do?
Have been looking at duplo stuff on Ebay -- lots of airplanes, tractors, that kind of thing. That would be £5-£25, depending what you got.
A BIG fire engine, well-made with bells and whistles (literally).
Anything airplanes or helicopters (DS has almost none).
DVDs: Long list, including Peter Pan, Finding Nemo, Wild Thornbury's, Bambi (DS really liked Bambi, honest!). Isn't Jungle Book out on VHS, but not DVD? I'd get that if we had a VHS player.
Age appropriate Computer games -- Nick Jr. sells a CD of games available on their website. So DS stops using the broadband to play games!! I don't know exactly which games are on which DVD, but the Dora The Explorer games ( probably here and here ) are really good.
Miscellaneous: Anything trains or diggers; A kiddy torch (we have one that changes colours and is pretty robust against being dropped, but its wiring has gone loose); Toy tanks (Tesco does some) with soldiers; Roller skates (not sure about price, though); Pirate ship (Argos do a combined Pirate ship and Castle with people, bits for £25-£30); A Pop Up Tent; DS has a concrete mixer lorry from the toy library that turns the concrete, has lights, rolls forwards and backwards. DH reckons DS is ready for starter-Scale-lectrics type stuff, but not sure on prices, there.
We are making a toy airport for DS, and the materials probably won't come to more than £15; just labour, really.
I have an even longer list for DD