I'm influenced by what's on sale, but don't buy junk of course. Delara's at 50% off is a steal. Vale of Twilight and Gianthold are top priorities (try for on sale). I'd say the best adventure packs after those are Necropolis IV and Sands of Mentecharum. For monks specifically, try to get Sentinels (for Jitz' tetka bracers) and Necropolis II (for Devout handwraps, though they're a pain to get). 32 point builds, as others have said, are extremely useful for monks, but with enough patience you can get them through favor.
By the time you've got the other stuff, hopefully you'll find monk on sale. If you're trying not to spend much money, that's the way to go. It's pretty easy to go through even 6900 points for the on-sale $50 bundle, so if you want to stretch 2000 points you have to be choosy and patient.
Even though it hurts in you budget: I'd buy Deleras as long it is on sale. It has tons of XP for toons at level 11 and below and great rewards (e.g. Voice of the Master, Carnifex, ML +3 stat items). It is too cheap right now not to buy Deleras right now. I say GH before Vale because you play the latter later.
Get Vale
I hit lvl 16 on f2p content w/o doing quests more than 3 times (n/h/e) and many quests I only did once or twice
Lvl 16 lets you get in groups for vale quests and do vale slayer. Both of these will get you to lvl 20 and get you access to the most important raid in the game. You also get access to 2 other very nice raids (HoX and VoD) which require no flagging, have some very nice gear (tharne's goggles, levik's bracers) and are fun.