What can dd get my ds (5) approx ?10-?20

[Debbiethemum]

We will be getting him some K'nex - the ferris wheel one and the 'Hot Wheels Shark Park' which looks fun. MIL is getting him a dressing up Outfit (I forgot that I needed to choose another present for dd to give him). He adores Lego & K'nex but don't want to get him more of the same - Please does anyone have any brilliant ideas. Space is limited in our house so it needs to pack up small, also both DD & DS have spring birthdays so outdoor toys tend to get saved for then.
DD (2.5) is getting a wooden hobby horse & 'Fifi and the flowertots' cottage from us and a dance mat/keyboard thingy from DS.
DS's presents cost a bit more than DD's so it doesn't have to be expensive but it has to be good
I don't know if DS is old enough to count presents, but he does like to know who gave him what (Stockings come from Father Christmas) so if we only give him one and dd 2 presents he could easily notice, but he has no concept of the cost.

How about walkie talkies?
DVD?
Is he into any specific thing - power rangers / spiderman? some of the figures for these are within the price range.

do you know I've never thought that the kids should get each other presents! And I will put that thought away for a while longer I think!

A board game? I'm thinking of getting my 5 yr old Junior Scrabble...

Uno cards are good too (but are a lot cheaper than 10-20)

shark park is 9.99 at toys r us! Tescos are doing this one for £20 at the moment!

Thanks Zubb, but dh has walkie talkies (so they already belog to everyone). DS is into power rangers in a big way, always drawing pictures of them, but already has a power ranger figure and just never plays with it.
He loves K'nex, Lego & Geomag and has quite a lot, well I have more Geomag but we play with my set together. Is two lots of K'nex too much do you think?

I am just too slow at typing - just seen all the other messages. Furball, I had already seen the price at ToysRUs for shark park, didn't realise Tesco's was so much more expensive.
KTeepee, I might go for a board game, it's difficult as DD will insist on playing to and won't play by DS's rules, which sometimes bear no relationship to the actual game rules.

the tescos one is a different bigger hot wheels (gorilla attack) and is reduced in toysrus to £29 but only £20 in tescos

The tesco's one does look good

How about something like this - £14.99, available from Sunday? It does say 8+, but I know my 5 year old can operate these ok once it's been set up for him, so the age is probably more to put it together than to operate it IYSWIM.

This is going to sound so wierd, but is another 'toy' that dh has, and we all play with. It is otherwise a brilliant idea as ds absolutely loves it.

How about some \link{http://www.platform8.com/acatalog/Online_Catalogue_Sea_Life_27.html\sharks? These are pretty much indestructible and much nicer than the ELC stuff.

Doh!
Educational sharks

Sorry Bucketof.... the link doesn't work
Actually thanks to everyone who is trying to help, I am really trying not to pour cold water over every idea.

Try again