Substitute for Gruyere Cheese
You’ve put us in a terribly awkward position. Gruyère is not a type of anything. We consider it among the top five cheeses in the world. Also, it is not made in Switzerland and France, it is only made in Switzerland, in the cantons of Fribourg, Vaud, Berne, Neuchâtel, and Jura.
Swiss Gruyère received a special designation in 2001 from the Swiss government, the Appelation d’Origine Contrôllée (AOC, or the controlled name of origin), which is only given to products are made in traditional ways and only in specified locations. The Swiss designation mirrors similar standards in use in other countries. There are faux Gruyères made in other countries, but if Gruyère gains “designation of origin status” from the European Union, no other country in Europe will be allowed to use the name.
There are French Gruyère-type cheeses, called Comté and Beaufort, and are required by law to have holes in them; real Gruyère is required by law to have no holes. (And you think this country has a lot of laws….)
Now enough about our fixation with Gruyère. The best solution to your problem, of course, would be to disinvite most of your guests and have a Gruyère feast by yourself or with one or two special guests. If that seems a little impractical or it is too late to do so, of course you’re going to substitute some other firm, good-melting cheese that you can afford. It will certainly not ruin your dish.
Make the recipe for yourself in a couple of weeks with Gruyère, though, and see if you don’t notice and appreciate the difference.