Mechanics please answer...?

[the biz 2]

I had my neighbor (who is a mechanic) look at my car because every now and then, when I turn it on, there is a rumbling sound as if my car is trying to turn on but wont. Eventually when I keep trying it will turn on. Well, after he looked at it he told my bf and I it was the solenoid in the starter that was malfunctioning. He told me if I could find and buy just the solenoid it would be cheaper but if not i'd have to buy a whole new starter. I called my other mechanic today to get a second opinion and they said sometimes you have to buy a whole new starter. So my question is this: Do you think I should buy the solenoid (which is what really is causing the problems) or buy a whole new starter which costs a lot of money?