My husband and I use a lot of small white envelopes for business. We have tried several different brands of envelopes but found that most of the others are not as sturdy. After some mroe shopping we found that Pacific Internatonal does the job for us. They are very sturdy and the glue on the envelope holds when moistened.
For one box of envelopes we get 100 of No. 6 3/4 white envelopes for 1.00 at The Dollar store here in town. We have not had any problems with them falling apart.
You can buy this brand in several different types, including manela envelopes, larger legal size envelopes, or the envelopes with the windows in the front.
I would reccomend these to anyone who is looking for a nice sturdy envelope at a decent price whether you use them for business or other types.