"Prix d'achat" would be "purchase price".

I am just a bit lost as to what kind of stamp you are referring to? A postal stamp. If so, "700 F" will be fine by itself.

But the meaning of this phrase is that the purchase price or value is 700 F.

Since it is in a stamp firms may indicate their gross sales figures/turnover ?

or you could say 700 Francs' worth of purchases, but that might defeat your goal of saying it succinctly!

First I thought ýt was written on " seal " of company or some such stamp.
It is royality coupon and may used as "700 F coupon ", but since it is an explanation of 1 Loyality coupon = ..700 F d'achats ( from your prev. question) it may be any explanation as proposed, worth.. or others, since it is explaining something ( may be in either form)
Sample 1 below (GM) shows an original usage .in second used as .. trade coupon.
Commont thing : They do not give this coupon as " cash " or convertible to cash. just a DISCOUNT on second purchase.



GM Restarts 'Loyalty Coupons'

General Motors Corp. has reintroduced a ``loyalty coupon'' program that set off a heated battle over customer incentives
among automakers in 1998. But GM and industry analysts said Wednesday the new coupons were meant more to shore up
GM's customer base than to start a rebate war. GM said the $500 coupons were mailed to millions of customers who bought new GM vehicles and to potential customers who tell the company they're interested in a GM vehicle. The money can be used toward the purchase of a new vehicle or for extended service and warranty plans. The offer expires Feb. 29, and applies to all GM products except Saturns, Saabs, Chevrolet Corvettes, AM General Corp. Hummers and several full-size sport utility models.

As I understand it, this is one of two things, although more context would have helped!

- proof of purchase
- voucher / coupon

It could be proof that the holder has spent 700 F and is thus entitled to various special offers, for example.

Much more likely though, it is a voucher enabling the holder to obtain up to 700 F worth of goods, part of some promotional offer.


www.fantasyisp.com/prize.shtml

We will announce the winner. There will only be one prize of the £70 voucher and in case of a draw between the top 2 Fantasy ISP …


www.users.waitrose.com/~tenterdengc/howto.htm

Enter our prize draw - £50 gift voucher - Click here for details. Home.
From Tenterden take the B2080 for 2 miles. We are on the right. ...


www.suntext.com/vouchers.html

Details using the form below and we'll send you a FREE Suntext Holiday Voucher worth
50 against the cost of your holiday with us! (Subject to a Minimum Total ... )

Difference between "coupon" and "voucher", if any, as they are pretty much synonymous.

Coupon : something you cut off a product's packaging to obtain a reduction of next purchase

Voucher : Something you obtain as a result of having entered a draw, sent off a form etc...