"Please ... I will buy it." Here, "sehr" is not translated, it only intensifies "bitte", which means "please".

The context is very vague but the situation appears as follows. A customer in a shop has chosen something for him/herself to buy and comes up to the shop assistent saying, " there you are/here we go, I' m buying it." It's a very contextual translation. You might also try "you' re welcome" if it fits the situation.
Surge

I agree with the above answer (no. 2), and would just like to add something:

Bitte sehr - here you are

Bitte - please, or you're welcome

sehr - very

As usual, it all depends on the combination of the words.

HTH,
please very, :-)
Sibyl