why to go to USA/Canada
I really don't see lots of benefits of going to USA/Canada. Well, better climate. But not really prices.
In Europe there are economical possibilities to get trained and become the ATPL.
From 0 to PPL - 6000Eur and from PPL to ATPL (200hrs, MEP, CPL, IR) - 21000Eur.
By the way, Avioservice (Latvian flight school), whose prices I mention they work with OAA and students get the OAA papers.
If I can share my personal experience about OAA - they do a really good job. Not a bad choice at all.
Good luck!