You can see the pricing page for the 30-day search API here. Hit the Select option under the Premium column to open out the month-to-month pricing tiers. Note that at a premium tier, in every request you can get up to 500 Tweets; however, if you need to do this on an ongoing basis (i.e. 150k Tweets every 15 minutes), you’ll run out of your monthly requests very quickly…
There’s no premium option available for 7 days at this time, but there is something on the roadmap.
