Some things have substitutes that are acceptable, depending on use. The only real way to know is to try. In some cases the substitutes will turn out not to be suitable (varies with taste, opinions, etc. - not something you can really depend on anything but your own experiments to know for sure.) I find a particular low-end-brand of creme de cassis to be superior for my purposes/tastes to several supposedly higher end (and certainly higher priced) versions I have tried occasionally. For other things the definitive brand is well worth it (and was even when I was in college/on a tight budget), at the rate I drink, anyway, and clearly superior in taste (to my taste.)
Some liqueurs can be be effectively knocked off with vodka/grain alcohol, sugar, and flavorings/fruit, (often +time) if you are on a budget and like projects. I did a pretty satisfying plum "wine" (as it's typically called) that way, but it took about a year to do, which might be beyond your planning horizon as a college student. Things that don't involve steeping actual fruit can be much faster, but might not save much money, depending on the cost of the flavoring(s).
At least of the bottles I have had in stock, Cointreau and triple sec are rather different, though both are orange-flavored, with the Cointreau being 40% ABV while the triple-sec was either 15 or 7.5%. Your linked version is 35%, so that obviously varies. Quality of the fruit flavor and lack of off flavors will matter more than the precise alcohol content, generally.