Lets say so, on long term is better to not buy any of those two but there are some considerations to do.
First: even if is true that gnw tenten can be pulled off edo tensei treasure you still have to use scrolls there that is something a f2p person should avoid as a plague. If you are wise and you plan to use scrolls only on kage and jinchuriki treasure then at most what you can get by luck is a 2 star gnw tenten out of a free draw that maybe happens next year, and you want her at least 3 stars to make anything useful out of her, so, imho, ia better to spend 900-1200 coupons to get her and eventually save 300-400 coupons for next time she appears in your road to 3star her if you are lucky and get her as free pull.
Second: You get 10 free fragments of iruka every 3000 refinement points you get. After 4-5 months of playing you'll be easy able to gather 300 points per day, after 7-8 even 400-500, so he will be 4 stars a lot sooner than you think and for free.