Q: Took my car to the only VW dealership in my town to get inspected. Was told to come pick my car back up as they did not have time

The N80 valve is a "purge valve" located on top of the engine. It is a very simple component in the EVAP system and indeed you can easily replace it yourself. The only way to ensure that the N80 valve was in fact defective, versus another vehicle component, is to ask the mechanic to demonstrate and explain, that is substantiate, the alleged failure of the component. The solenoid (N89) that you are referring to is in the transmission but the code referring to this solenoid can set for many reasons (i.e., the solenoid is not necessarily the defective component or "cause" of the fault). Consequently, once again, if a part such as the solenoid is claimed to have failed ask for substantiation. The technology used in Volkswagens is basically the same as that used by Toyota, Ford, GM, BMW and on and on and therefore you might want to consider looking for a less costly repair service; you don’t have to rely on high cost dealerships that have tons of overhead (but do offer free coffee...LOL). With regard to that $50 gas cap, the cap seal is vended separately by Volkswagen for about $10 (the dealer probably didn’t "mention" that) and it is the seal that goes bad typically not the entire cap. The reason the whole cap is available is mainly to cover those circumstances where the cap is lost by the customer. With regard to the present issue involving the transmission if you want the cause pinpointed and repaired economically on a mobile basis, right at your location, please request a Check Engine Light diagnostic and the mechanic will get this issue resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you save money.