I agree with NSK, the lot of French stamps, all the same, are very common, and you may get in the ballpark of $1 for them (or maybe not). The missionary cover is interesting, but I would not expect it to sell anywhere close to the listed price, maybe somewhere between $2-10.
You should consult a stamp catalog (Scott, Stanley Gibbons, etc.) to get an idea of the "retail" value (which is what you would expect to pay a dealer), for which the price you should expect to get on
ebay would be much less. Good luck, you may get a buyer, but I would not expect any bites at the listed prices.