How much does an integrated library system cost?

Could you please elaborate on the various factors that can influence the cost of an integrated library system? For instance, do the size of the library, the specific features required, and the level of customization play a role in determining the overall expense? Additionally, are there any hidden costs that one should be aware of when budgeting for such a system? It would be insightful to understand the range of prices that libraries of different sizes and needs typically pay for an integrated library system.