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I agree with pp it depends on your budget,Figure out what you can afford to spend in total and divide that by the amount of guests you will have..I did a candy buffet as my main favor,but then i did scented roses on each ceremony chair,A Spoonfull of kisses at each place setting and i also had gift bags for each guest filled with personalized hershey bars,mini bottles of wine,lotto tickets,wedding mints,and a thank you note....
I have almost 300 guests myself. Are you planning on giving 1 favor per guest or 1 per couple?
I am averaging about $3 per guest for 177 guests. Definitely do edible favors.
I'm doing personalized M&Ms, I think I'm ending up spending about $2.50 per guest :)