I think that all really depends on whats available in your area, and what your skills are in terms of rifle building..
Me personally, I'd probably look for an old military mauser that LOOKED like it had been beaten to hell... What you'll find is most pre WWII mausers were built extremely well (stuff made between 1939-1945 can be questionable for obvious reasons).. unless someone very intentionally abused them, they will almost always provide a solid foundation for a build assuming you can find one where the action and bolt (the only things you really want from the gun) have no pitting or other obvious damage to them.. the worse it looks superficially, the better.. you dont want the stock, trigger, barrel, sights, etc..etc.. anyway.. if you can find one that really looks horrid, chances are you can get it cheap.. (I find them here in the US for $200 or less regularly.. where "nice" looking ones typically are $350-$500.. and really no better suited for a build project than an "ugly" one.. )..
But this leaves you with having to do a whole lot of work.. or paying a competent gunsmith for a whole lot of his time.. which can be costly..
The only special tools you really need are an action wrench (about $60) and a bench vise ($50 will get you one capable of handling the task if you dont already own one), a set of punches ($20 if you dont already own a set), and some basic wood tools for stock work (I did 90% of the work on mine with a dremel, and the remaining 10% with small hand files).. you'll also need to rent a chamber reamer and a set of go/no-go gauges (about $60 here in the US)..
For me, as I have stated before, I really enjoyed the build process, and I get a lot of happiness in knowing that I personally built the rifle, that I personally tailored a specific load for the gun and assembled the cartridges, etc.. and was able to do all the work myself..
But others may not find the build process all that rewarding.. If youre one of those guys.. I think you might be better served finding a a rifle that you are already satisfied with that just needs a rebarrel.. I think that would be a much more affordable route.. If you have to hire a gunsmith to do all of the work laid out above, between parts and labor, youre going to hit that $3K mark pretty quickly.. and would have probably been better off just ordering something new, or doing the rebarrel on something you know you already really like..