WAP the hell?

[ffutures]

I'm finding the WiFi signal in my flat gets a bit poor by the time I'm out on the back roof, and looking at three main answers:

1. Move the router / transmitter and see if I get a better signal (needs several longer network cables, an extension cable for the router's power supply, say £10-15 all in)
2. Put another wireless access point in the back room near the window, to extend coverage to the roof and the garden below. Preferred solution, but probably the most costly since I can't find a WAP under 45 quid.
3. Run a length of CAT cable out to the back window so that I can plug the laptop in directly, thus avoiding the problem completely. Probably eight or nine quid for cable. Undoubtedly the best option in terms of speed, but it feels a little inelegant. However, I may want a network point there eventually if I ever set up a dedicated computer for TV recording etc.

Can anyone tell me why a WAP costs considerably more than a router with WAP built in (Linksys currently £36 from Amazon)? Also, is it possible to daisy-chain two routers, thus adding four more network sockets as well as the WAP, or would the second router's firewall get in the way? No urgency about this, but opinions would be appreciated.