The nice thing about Allegro is that you can at least start with one of the cut-down variants and work your way up. The learning curve is very steep, but it may be the last tool you ever need to learn.
I use Orcad PCB Designer, which is the exact same tool but with the expensive options disabled. It's still a hugely capable piece of software, though, and it'll load, save and edit Allegro board files. Moreover, it's "only" about £1500 (including Orcad Capture for schematics), which is more than the hobby grade software but much less than most other professional options.
The costly options begin with things like length matching, differential pairs and other fairly basic functions, but go all the way up to advanced simulation, collaboration tools, automatic multi-channel placement... all great time savers if you're doing complex boards all the time or if you need advanced analysis. For a single user working on the kinds of boards that one engineer can reasonably develop alone, these features have much less value IMHO. And yes, the costs of the top-end variants really are from another planet entirely. I beieve some of the options aren't even offered for outright sale, only rental.