How much do you know about RS GOLD?
Even with prayer potions, you will probably profit from slayer, they are fairly affordable. From the drops alone you should gain, and if you do not have that then purchasing Slayer Dart runes in the slayer master for 35 slayer points (you receive 36 for performing two jobs from Kuradel) gets you around ~70k that is adequate and can add up to OSRS gold if you spend your money on this instead of cancelling or blocking tasks.
Rnging it will get u killed cuz u can't weild an anti drag sheild (unless u use bronze bolts with a reg crossbow), which I truly don't advise. Maging it will be awful as I read tht it has remarkable magic def. . U also require the anti drag sheild, as without it, elvarg can hit 500 dmg.
Also, get a full inventory of lobsters/swordfish. Swordfish is a lot better, but killed elvarg at around 40-50 combat, using just 3-5 lobbies. This installment is just for the last boss fight against elvarg the dragon btw. One more thing, having 33 magic can save 10k gp (such as telegrabing a map bit rather than buying it from the goblin). Also bear in mind, u need 33 quest points to even begin this exploration. If u wish to, don't hesitate to contact me in game (Tarun Dragon) and I would be more than happy to help u, and finance , if ur not great on money. The entire quest costs around 50k, to 60k. When I did this, rune scimmies where 60k on its own, so it cost me much more.
Everyone has given you the very best advice, except for two things. I believe an amulet of electricity would be much better than power, as it boosts you precision and defence. A short sword will beat a scimitar against dragons, who are feeble to stab strikes. I wanted to mention this too, though I forgot that he'd need the extra atk in his lvl, and yeah, dragons are rlly weak to stab (was trying to think of an f2p stab wep, but cudn't lol).
If u do use a rune sword be certain to get it set to a stab atk btw. Its still slower and weaker than a scimmy, on the plus side, u might strike more often, and its cheaper. Btw, if u get 43 prayer, u cud practicly kill it without needing any dmg watso ever lol. But do not, u rllly do not need prayer to kill elvarg.
Oh, too, when ur doing melzar's maze to get part of the map to crandor, it wud be best to secure spot the Demon (80+ cb) with mage, so bring along with a 100 chaos runes, with an air staff, along with elemental runes, or bring 150ish mind runes, together with air personnel and Cheap RS gold the very best elemental runes tht u could use. (if ur using mind runes, utilize atleast the flame attack spell, as the reduced ones might really do lower dmg than the lower demon's hp regen rate. I personally didn't understand what I was up against, and had to melee it, bk once I had been doing the quest. It was really tougher than the boss battle against elvarg.