vinster29

I have a 99 Lexus RX300 that will not start. I thought it might be a dead battery but when I tried to jump start it, all I heard was a grinding noise coming from the engine area. I think my starter might have gone bad. Any ideas on what the problem is? I only have 50,000 miles on my RX so I think it would be a little premature for the starter to go bad. How much does a new starter for an RX300 cost? Any help would be appreciated. Thanks.