Have you considered having a picnic on the Eiffel tower grounds? My friend and I were there last spring and we had the best time going to a local market and picking out the the most beautiful olives, calamari, grapes, and a variety of cheeses. Of course we paired it all with fresh french bread and red wine! You could spend hours enjoying each other and delicious french food with a gorgeous view ... all on a budget.
I'd recommend also seeing the tower at night as it sparkles so brilliantly!

Can I get a lunch reservation for 58 for July 2015?

Looks like it is too early. And I see that the meal, for 41€ is a picnic basket lunch. Now it's really not worth it.

http://www.restaurants-toureiffel.co...pril-2015.html

You can take your own picnic up the Eiffel Tower. The 1st level is extremely spacious.

Note that the 41.5 euros gets you a picnic lunch with one soft drink or a glass of wine. No definition of what the picnic consists of.

Frankly I wouldn't go for it without more info.