Well you can think of it this way.
You have T1, T2 and T3 enhancements~
T1 is for weapon level 1 and for players level 1~20
T2 is for weapon level 2 and for players level 30~50
T3 is for weapon level 3 and for players level 60~79
T1 is the cheapest for enhancement and T3 the most expensive.
If you don't have much money I suggest you +9 a lv 20 item and use that til atleast level 40. From lv 40 you can level quite fast in the abyss. So maybe just get a good end weapon and form a party there.
Save up for T2 enhancement for Lv 50 weapon and T2 enhancement.
Once you get to T3 enhancement. It can cost up to 6 gold for a complete +9 enhancement from +0. So you can use the money you've saved up from not buying enhanced lv 30 and lv 40 plus the additional drops you get from the abysses.
Just my advice
Hope i've somewhat helped you
