Done all of them up to the League and Nation hybrids. Russian League, Argentinian League and Mexican League, and French Leagues have been my main starting point. Packs have been decent and I've made 50k since yesterday morning and have a load of stuff in my club that can be sold as well when the time is right.
First attempt at the Not Easy challenge and I came up with this:

https://m.imgur.com/gallery/co91rPq

Only Dzagaev cost anything (1.5k), and all the right hand side and keeper were for between 150 and 350 coins each. Cost about 4k and had a packed Kerzakhov. This has been one of my cheapest ones and was pretty pleased that it was so cheap!