Upon closer examination of the TJs receipt, it turns out they actually charged both boxes as one item, so it's actually $2 there for 5oz/142g of jelly bellies. That comes out to $6.40 a pound.
coraa reports that Costco has 4 lb containers for $15, or $3.75 a pound. So even correcting for my earlier error Costco is much cheaper than TJs (big surprise =) although the TJs boxes only have 20 different flavors, most of which i like, while the Costco containers apparently have 48 flavors, so i'd have to see how the mix compares.
Both cwendy41 and i independently got the idea of checking the Jelly Belly website. If you want individual flavors you can get them in various sized packages ranging from about $8 to $10 a pound. So definitely more expensive than either of the other options. Still, $9 a lb for a mix of Juicy Pear, Watermelon, Green Apple, Cotton Candy, Bubble Gum, Blueberry, Wild Blackberry and Top Banana doesn't sound too bad to me :) Of course the real question is do any of the stores that sell them in bulk have them for anywhere close to that price? A small increase would certainly be worth it of course just to account for what i'd have to pay for shipping if i ordered them direct.