"Be reasonable"

When I first started talking to my parents about a wedding budget, they had no idea what to say. I started just randomly throwing numbers out there to see if I could get a solid number to stick to. I never was able to get a firm number on it; they just told me to "be reasonable". What? Is all I could think. What does "be reasonable" mean? It's frustrating when I'm trying to book vendors for the wedding. Is $x,xxx "reasonable" for live music during the ceremony? I'm trying to cut costs as much as possible with things like buying bulk flowers and having a friend make the arrangements, but it's starting to stress me out. Give me a number people!!! I'm going to ask once again tonight if I can have a solid number to budget with. Wish me luck!