input: [Benefits?] Generally cheaper than pay per click, especially after the first year. [Risks?] Many firms charge rates as though an expert is working on your site, but have under-trained college graduates and interns working on your site. If search algorithms change dramatically they are required to service many clients at once. Hopefully you are paying them a lot of money so you are high on their priority list. If not, then you might be stuck buying a lot of paid search ads and/or firing some of your staff. Some SEO providers lock you into their proprietary systems. [Service] 
output: Average SEO Provider
options: S E O B o o k M e m b e r s h i p
options: G o o g l e A d W o r d s
options: A v e r a g e S E O P r o v i d e r
options: L o w E n d S E O P r o v i d e r
options: S E O C o n f e r e n c e s
options: H i r i n g a S E O M a n a g e r
options: O t h e r S E O T r a i n i n g S e r v i c e s