With the data you provided is kind of hard to come up with a price tag.
For a Ground Station you usually need the Antenna, Tx and Rx amplifiers, filters and other radio hardware, dedicated computing power to encode/decode the transmissions and perform error correction. And the performance of the whole system can vary considerably based in a series of communication systems' parameters that can be configured.
- Error correction codes.
- Carrier Frequency
This is by no means an exhaustive procedure, but to put a price on something like that you'll have to first define a whole set of operational constraints and requirements for your operation and work backwards from there.
- What frequencies do you want to communicate in?
- What's the maximum amount of spacecrafts you want to communicate with at the same time?
- Maximum bit rate?
- What communication standards are you going to support?
- What is the maximum acceptable Bit Error Rate for TX and RX?
- What is the worst communications system a spacecraft can have and still communicate successfully? (Weaker transmission, minimal error correction)
- From a single point on Earth the moon has direct line of sight only during a few hours a day, what percentage of that time window do you want to be able to reach the satellite?
Start by taking a look at NASA and ESA communication standards (ESA). Then check the technical papers for the missions you're interested in to get a grasp of their communication systems. Come up with the main operational scenarios you want to cover and perform link budgets (Link Budget) (Required power at receiver vs Received power), for the worst case scenarios (weakest spacecraft comms systems with minimal error correction and the maximum link distance) using different antennas and amplifiers configurations. There are online tools (Link budget calculator) but is better to have someone with enough background to understand this to assist you in the process.
Once those questions are answered, you can come up with a price tag for the main components for your GS:
- Antenna(s): Minimum diameter
- Antenna(s) motors: Based on weight of the antenna, and required motion range
- Antenna(s) control system: you need a way to target the spacecraft.
- RX and TX amplifiers.
- RF Filters.
- Hardware required for error correction and signal recovery.
- Station power systems.
There are several ways to implement equivalent systems, and each design will have their one trade-offs.
Hope this helps!