What would be the quickest way to lvl up for me, and have it still be fairly cheap?

Smithing is just not "fairly cheap". Mithril bolts used to be decent for not losing much money, otherwise make the best thing you can.

Goldsmithing is expensive, so I guess you don't want to hear that.

 

 

 

You could try steel bars, smelting cannonballs perhaps.

 

 

 

Goldsmithing is the way to go tbh.

World 58 Blast Furnace.

 

 

 

 

 

 

 

Make mithril bolts(u) until you can make mithril plates. The bolts stack, and you alch the plates. Plates are faster XP hence the switch.

 

 

 

 

 

 

 

You only use 2 coal for every mith, so you'll profit slightly.

 

 

 

 

 

 

 

Theres a decent guide on here if you search for "blast furnace"