You can easily spent £25 on a large spirit level. Even a cheap 60cm one costs £10.
Since I have some plans to build a wall across uneven ground, a long spirit level to check my footings are level is a requirement. But I didn't want to spend a lot of money.
So I went into B&Q and, for £5 plus a few tens of pence, picked up a two-metre length of extruded steel box section, a square tube about 1cm on a side and strong enough to not flex noticeably under its own weight.

And for about £2.70 I picked up a small hand-held magnetic spirit level unit.

Combining the two, voila - for under a tenner, I have a two-metre long spirit level.

And although there's only two vials in the magnetic level unit, it has the functionality of a level with lots of vials, since I can position those two vials at any point along the level I require. So I can have them in the middle, for traditional "is this rubble-filled trench roughly level" checking. Or, when nailing a series of pegs into the ground and wanting them to all be at the same height, I can bring the vials to one end of the steel tube, balance the other end on an existing peg (ideally with a helper to hold it there!), and easily read the vials as I adjust the peg I'm leaning my end of the tube on.

And when I'm sick of building walls, I can store the pocket-sized magnetic level away, and think of something useful to make with two metres of steel square tubing, an arc welder, and a brazing set...
To stop anymore cat wee incidents I have become a tad militant - and thus we have been focusing on doing something to the bare wood units we have in the lounge.
Here are photos of the first unit being dealt with.

First off we had to sand the cube all over - especially the edges as these are manky loose grain pine which splinters like anything!

Then we had to dust the saw dust away!

Then to the vanishing - we decided upon silk finish - it took four coats! Still I had estimated 5 coats!

We did everything but the undernieth surfaces, then when dry turned it over and did those - but we then repeated the processes with out turning it over so that there was less of a chance of ending up with a good top and bad bottom - not sure if that makes scense but thats how we're vanishing these babies!
Power had returned when we came back:
Mar 5 19:18:42 anger upsmon[703]: UPS powermust@localhost on battery
Mar 5 19:22:02 anger upsmon[703]: UPS powermust@localhost battery is low
Mar 5 19:22:02 anger upsd[718]: Client monuser@127.0.0.1 set FSD on UPS [powermust]
Mar 5 19:22:02 anger upsmon[703]: Executing automatic power-fail shutdown
Mar 5 19:22:02 anger upsmon[703]: Auto logout and shutdown proceeding
[...]
Mar 6 18:54:33 anger syslogd: restart
Mar 6 18:54:33 anger /netbsd: NetBSD 3.0 (ANGER) #2: Sun Feb 4 19:20:11 GMT 2007
The day's work can now begin... I can run the computers or the ADSL router off of the generator, but due to cabling limitations, not the computers and the Internet connection.
Bah. Our power failed at 7:30pm last night (the 5th of March) and has yet to resume at the time of writing (11:30am on the 6th of March).
The house is festooned with extension leads, since we're running the fridge and freezers from the generator, with another spur over to the ADSL router zone. I'm typing this on my laptop, hooked up to the router with a patch cord, since I don't have enough extension cables to get the switches going to get Internet access to the office...
About to go out and fill up our fuel cans...