I'm new to product advertising and am interested in advertising on google but I was wondering if it is expensive and is it worth it to invest in it?

that depends on your keywords.

I get a better ROI with exact seek Paid for position ads.

AdWords is really only as expensive as you want it to be. you can set daily and monthly budgets on it and when your ads reach that budget Google will stop showing them until the next day or month.

As for how well they'll work that will depend on how well you use the system, what keywords you choose, how much you bid, how well you write the ads, etc.