Some organizations have a combination of plans. With transactional pricing, you incur a charge every time a new search is entered. You can view your search results for as long as you want with no additional communications or database charges. Under these plans, start with very broad searches and then narrow them using locate or focus rather than starting new searches. The price per search depends on the file selected.
Hourly pricing is based on the size and perceived value of the file or database.
Larger, mega type files and public record files are more expensive. Get offline as soon as possible. Better yet, print a cite list and read the cases or articles in hard copy. Hourly rates for government agencies are significantly discounted. More and more organizations are opting for fixed rate plans which are based on anticipated or past use.