Is 6-10 shillings a lot of money in Shakespearean times?

Yes, that was quite a lot of money. Ten shillings was the amount of pay a skilled labourer (we're talking a union man here) would get in a biweekly pay period. Six shillings was five percent of an unskilled labourer's annual income.

Also bear in mind that a shilling could buy you about six loaves of bread and twelve dozen Apples.