A chap I work with recently got a Kowa 2nd hand in a local charity shop for £75. I don't know much about their model range but it was in good condition and has nice optics, pretty amazing optics for £75. They come up now and again on ebay but usually do over £100 from what I can see.
The other thing you might consider is a draw type scope as you could use it for stalking or could mount it on a tripod for your target and zeroing days. Nickel and Hertel and Reuss are two names that come up pretty often on ebay and they are worth £50 - £100. Occasionally you see people bid crazy money for them but they simply aren't worth it. I recently picked up a Hertel and Reuss in not great cosmetic condition for less than £60 and it works well for my purposes. The advantage with them is that they were good quality German engineering in their day and even though they are 30 years old now a decent one should work well for you.
Another step up with the draw scope type optics is Optolyth and they tend to do more money with the 2 draw 30X60 coming in around £250 - £350 usually. The 30X80 Optolyth is bigger and heavier than the likes of Hertel and Reuss which might be a factor if you wanted to take it stalking, it is also shorter when extended and that makes it more difficult to rest on a knee when lying down spying.
There is a place in Glasgow, "Glasgow Binocular Repairs" which can do work on most of the draw type scopes and they aren't hard to pay so providing there isn't a serious fault a Nickel or Hertel and Reuss off ebay for less than £100 can be good value and, when you have the cash, you can pay another £70 to have it cleaned and serviced and have it working like new. Clearly you'd be hard pressed to find someone to work on some cheap Chinese "no name" scope.
