Coolant Regulator Valve

I have a 2004 Toyota Prius which has recently been giving me alerts (the whole exclamation point in the triangle and the engine light coming on) so I went to the dealership so they could run some diagnostics. The dealership diagnosed it as needing a new coolant regulator valve, they said the one thats currently in the car keeps getting clogged or something like that. I went to a Goodyear today to see if they could give me an estimate on how much it would cost for them to replace the part because I was looking for a cheaper option. After Goodyear looked at my car, they said that my car was leaking a little bit of water and coolant. They refilled my car with coolant and now the engine light and alerts are off. The Goodyear mechanics recommended that I get a new water pump for my car instead of replacing the coolant regulator valve. I was wondering what I should go with, the coolant regulator valve or the water pump?

 

Toyota quoted me $500 for the part and the installment. I already bought the part myself off of ebay for about $85, but once I looked up how to repair it, I think I bit off more than what I could chew. Shouldn't the toyota dealership know which code is giving the issue if they ran the diagnostics?

 

Im not guessing at it. I went to the toyota dealership and spend $120 for diagnostics and they told me that the coolant regulator valve was the problem. But since the people at Goodyear are telling me that its a water pump problem, I got confused.