I don't know if the valves are entirely to blame. Most people change their oil and the ticking will go away. I have the same problem right now and already did an oil change almost 300mi ago, but I let my engine run pretty dry and didn't really go easy it on her. Plus I was having issus beforehand where I had loss of compression in my 3rd cylinder and had some oil on the spark plugs. So I probably blew my valves but my lifters could have siezed up too. Either way if an oil change doesn't fix your problem be prepared to re-do your top end, which can be expensive if your looking at replacing with performance parts like MWR stage 3 cams and valves, which will run like 2-3000$. I personally feel that an engine swap will be the cheapest fix. EBay motors has the 2zz-ge for like 1200$ tops, some as cheap as 800$.