Don't forget to consider further afield when contemplating where to go to do something bigger, longer, harder, remoter or different. For example, using Calgary in Canada as your destination airport you have the Canadian Rockies before you. Vancouver could also be used for other mountain area options. Another option is to find good deals for further onward internal flights within Canada to destinations like Whitehorse, Dawson, Fort McMurray, Fort Nelson or other off the beaten track places.

Although prices vary depending on day / date of departure and return, and other departure airport options might also affect price. A typical return flight Glasgow - Calgary in May with http://www.flyzoom.com/  for 2 weeks or so will cost about £422.55 based on Economy Standard (cattle class). That's a fraction of the typical BA or other scheduled airlines [BA price for same journey same dates (although has to be via London) is £650.90].

Try jet2 into Biaritz then go to the Pyrenees or even the Picos de Europa. Its a newish route so you might get some very good deals. Also, Biaritz is a good area for surfing so you can try that too.

Marrakesh is now a cheap airline destination and there are many options for trekking either alone or using local trekking companies (be careful). Some of these are actually run by English ex pats, they are often a lot cheaper out there than using UK trekking companies and at the end of the days the UK based ompanes sometimes use the locals anyway.

Budget arlines fly to Barcelona (or Girona), where you can grab a bus into the Pyrenees. I caught the bus to Benasque, where I started out. There were plenty of peaks and trails in easy reach, a good network of refugios and tonnes of places to wild camp (the cheapest- my favoured option!). There's quite a few other bases throughout the mountains though. Plus Barcelona is a great city to spend a couple of days after, if that's your cuppa tea (it's blooming expensive though!).

There are so many options though. Enough to boggle the mind! Good luck!

The Tatra.  Imagine the Cuillin of Skye times two (a 26 mile complex ridge of granite reaching  a high point of around 2500 m).  You can fly to Poprad and get a £1 train ride to the edge of the mountains.  Great hut system and still a pretty favourable exchange rate (a night in a hut with food about £7.50-£10).  There's a great hut to hut route, some equipped paths with scrambly bits and any number of summits you can easily reach on foot.  You might balk at little at the apparent regulation of it all out there (in the tatra national park) but its pretty light touch in reality.

Baverian Alps..Zugspitz...etc..gorge walking thrown in cheap flights from our friends at Lufthansa to munich 1 hour on the train to the mountains.