How much are old beethoven symphnony albums worth?

If you mean albums of 12" 78 rpm records, I doubt they're worth much at all. I have some too. The only thing that makes these worth anything is if they have some rarity value.

You'd need to give more details before anyone could give you any kind of proper answer. Details such as:

Label
Condition (MUST be mint)
Artists (orchestras, soloists, conductors)

Just for starters.

Edit
If you're talking about 331/3 LPs then the same criteria apply. It is pretty unlikely, however, that they'll be worth anything at all.

Remember, most noteworthy performances have been reissued on CD by now.

It all depends on the version, condition, age and other areas.