Your best bet is the flat rate box, which costs $8.95 to ship and it doesn't matter how much it weighs (up to 70 pounds). That box will easily hold 200 chips, and is available from your local post office. If you ship outside the USA, the rate is higher and a weight limit may apply.

Flat rate envelopes cost $4.60 to mail, but wouldn't accomodate 200 chips.

Post office info:
1.5.1 Flat-Rate Boxes—Rate and Eligibility
Each USPS-produced Priority Mail flat-rate box is charged $8.95, regardless of the actual weight of the piece or its destination. Only USPS-produced flat-rate boxes are eligible for the flat-rate box rate.

1.5.2 Flat-Rate Envelopes—Rate and Eligibility
Each USPS-produced Priority Mail flat-rate envelope is charged $4.60, regardless of the actual weight of the piece or its destination. Only USPS-produced flat-rate envelopes are eligible for the flat-rate envelope rate.