Tim Allwood said:
yep Tero
South America (Peru and Ecuador are good value)
Anywhere in the Orient is pretty good. Indonesia is wonderful, very cheap and the birds are disappearing fast. Whole Indian subcontinent is very good value, as are Cambodia adn Vietnam Once you take the plunge you realise just how easy it really is. And once tried, everyone goes back for more it seems
I couldn't have said it any better than above.
If you can find the money for a plane-ticket the rest can be done rather cheaply if your willing to "rough it" - the top birds are in those localities anyway. I have been on several top bird-tours, but mostly birded independantly in recent years... and it is a much more satisfactory experiance. Going out there, finding the birds yourself. It just requires homework (and is it really work when it's your own interets?). In recent years I have also been on the other side (being the guide) and I must say, that I have a somewhat hard time with the fact that many people who go on these expensive guided tours just put a mark in their book - not having a clue if the guide indeed is right. I actually had a rather laughable experiance in Ecuador where I stumpled upon a guided group. Suddenly the guide pointet; Tanager-finch! A real rarity. Everybody wrote it down in their note-book. Well, in reality it was a Black-capped Hemispingus! The people on the tour didn't seem to have a clue, they were just happy to get their much wanted tick. The guide claimed I was wrong, but when I pished the bird out... Black-capped Hemispingus indeed.
You basically pay for three things when you go on a top birding-tour:
1) The guide - do your homework (localities, voices, ID-features etc.) and you can manage without. For some parts of the world it is a very good idea to practice on the local language (ie. Spanish for South America) before you leave...
2) Top lodges - do you really need warm water in the rainforest? Most (but admittedly not all) localities can be visited via cheap hotels or camping. Do note that there are a few localities around the world where it is downright dangerous to visit without a local contact.
3) Private transportation - in many of these countries there are loads of busses going to every corner of the region. In some out-of-reach areas there are trucks or horses instead, it's all part of the fun! The minus obviously is time/speed: Private transportation usually is faster than getting there yourself. It should perhaps be mentioned that Africa in general is the exception: For many localities you DO need private transportation.
So, choose a country (I would recommend Ecuador, Peru, Venezuela, Brazil, Indonesia, Malaysia or Thailand) and start planning... it's much easier than you think...