I need to set up a marketing strategy to sell a very durable and reliable desk drawer slide for $8.75 when there is a competitor selling a cheaper less reliable version for only $1.75– obviously my product is better, but how do I stress that to customers and get them to pay this high price?

To market in terms of quality rather than price, and in order to differentiate accordingly, you need to follow the standard format of the 4 P's marketing plan. That is, Price, Product, Place and Promotion – obviously you know the main attributes of the product, and the price, but for ‘place' you should think about the type of people who are willing to pay over 4x price of competing product – whereas the cheap option may be sold where emphasis is on cost, your product will be suited to places/distributors where the customers will be willing to pay for quality. Promotion needs to concentrate on the unique selling point / differentiator of the product you are selling, so this would be promotion through media (the choice of which depends on place – ie internet, leaflets, direct sales force, tv etc etc) with a strong emphasis on the reliability, durability and quality of the desk drawer slide – heavily focussing on the life of the product compared to cheaper ones; a ‘lifespan' comparison could show the cheaper one to be a false economy both in cost and effort of replacement, so this could communicate it quite well.
Hope this helps 🙂