I shop in the shuk for my fruit and vegetables. If I taste the new fruit do I have to say shehecheyanu or can I wait until Shabbat or chag?

Shalom Shmuel, Yes, you should make the shehecheyanu bracha before the first time you eat the fruit each season, wherever you happen to be, and even if it's in the shuk just to taste, for you do get the pleasure (unless it's by the tree and you want to check if it's ripe, then you make the bracha only after ascertaining that it's ripe and edible). If they are selling it in the shuk, than it’s surely edible. I may add, that it's important to ask the salesman for permission to taste before you buy; otherwise, it's like theft, without realizing. With Love of Israel, Rav Ari Shvat