Skilling up Jewelcrafting
 

As a chanter, I am willing to start leveling Jewelcrafting.

I was wondering if investing all the skill points make sense, and if there is a limit on it. Any suggestion?

you can put points into in up to 21.
Anyway, if you plan to start it make sure you have the plat to finish it. There isn't much of a market for the lower-end items, so you won't make much money until you can profit from high-end combines.

Actually, selling the low-end items to lowbie players can net you a nice profit if it's your first character. When I started my enchanter, I ran a business in GFay selling silver jewelry for 5 or 10 pp/item depending on the item and I made a couple hundred plat profit. For someone with a level 50 alt it's nothing, but for someone who's level 8 for the first time, it's a big deal. Of course, you can also make money by leveling up and selling loot, but if you enjoy tradeskills, it's a fun thing to do from the get-go.

As for the OP's question, I personally invested skill points to get it to 21, but if you have some PP to get yourself started, it's not really necessary, as you can make back the money after you get your skill high enough to make silver jewelry trivially. If you don't have that initial PP (I think like 20 or so would be enough), it might be better to invest the skill points. The only real issue is that those skill points might be better spent boosting your Research skill, which has no training limit (though it gets mighty expensive).

what lvl of skill do you have to be to start making some nice mid range items? +4 int earings and such

3 stat ears are llike 60-90

how much would it cost me to get my skill up to around there?

There is a list of trivials and combines in the p1999 library. It is not 100% accurate and is missing a few items, but it is solid enough if you are just skilling up.