Hello Reekoh!
Archer isn't too expensive when you have a steady way for making gil (and you should have one no matter which job you decide to pick). It depends on server though.
You should start with buying the
level 1 bow and some
level 1 arrows from a NPC. The bow costs 816 gil and the arrows are 1 gil each (buy a few stacks). I recommend doing guildleves until maybe level 20 to fund your arrows and make some gil.
You can check
Moogle Box for bow and arrow updates. Don't have to update them every level though, just enough to keep your damage good. At level 25+ I recommend doing
Toto-Rak to get
Joukil's Guile, it's free and a really nice bow for that level.
If you haven't joined a Grand Company yet, I recommend that before you join one, you spend some seals you have for the other companies to buy Steel Arrows (115 seals a stack).
When you're a bit familiar with the job, I recommend you read
this great Archer / Bard guide by Carraway. It's mostly about playing the class at level 50 though.
To unlock Bard, you need to have your Archer at level 30 and Conjurer at level 15. Bard can use abilities from Conjurer and Thaumaturge (in addition to Bard and Archer abilities, of course). I recommend leveling Conjurer to at least level 34 for Sacred Prism (it let's you cast heals and buffs like Stoneskin to all party members nearby) and Thaumaturge to level 30 for Sanguine Rite (still haven't leveled my THM though

).
I wish you good luck on your quest - may your journey be full of laughter and great adventures!