No, there isn't
The rules published so far allows the PCs to only own one ship, and every mention of the party's starship is on singular (their starship). This suggests they can only own one starship at one time.
As the PCs go on adventures and gain experience, they need an increasingly powerful starship to face tougher challenges. When the characters’ Average Party Level increases, so does the tier of their starship. The PCs receive a number of Build Points equal to the Build Points listed for their starship’s new tier – those listed for its previous tier, which they can use to upgrade their starship.
Starships have no price because their power is relative to the party's level, a single BP at later levels is worth more than the same BP at earlier levels, because more (and stronger) options are available.
Personally, I believe the starship rules are somewhat simple in design, which allows for easy customization and creation of new rules. This means that we will soon see more rules about them.
However, this doesn't mean the GM could not work something out with the players, like splitting the BP or allowing them to command/lead a few NPCs that have their own starships (but not owned by the players). Splitting BP doesn't sound like a good idea to me, but it's something to consider because even if they have two starships, the PCs are still limited in number and couldn't possibly fully operate both starships without the help of NPCs (GM territory).
If you wish, you could make up a price based on the starship tier and BP points. First, do notice that starships get a big upgrade to their Hull every four tier increments (at 4th, 8th, 12th, 16 and 20th), at the same time they get HP increments, which we should call it rank upgrades to make it easier to understand. Then you can price it like 1k credits multiplied by the ship's rank and BP. So a rank 1 starship's BP would be worth 1k credits, while a rank 2 starship's BP is worth 2k credits, and so on. A few examples:
- Tier 1 starships (rank 1): 55k credits;
- Tier 4 starships (rank 2): 230k credits;
- Tier 8 starships (rank 3): 615k credits;
- Tier 12 starships (rank 4): 1,400k credits;
- Tier 16 starships (rank 5): 3,000k credits.
- Tier 20 starships (rank 6): 6,000k credits.
A common starfinder land vehicle costs around 1k credits, while a hovering vehicle costs around 15k credits. These prices are similar to starship costs in Fantasy Flight Games Star Wars: Edge of Empire system. This creates starships with comparable prices with anything short of dreadnaughts and similarly overpriced star wars ships.
But despite the name and size, a starfinder dreadnaught has a 500 crew limit, while a star wars dreadnaught has a crew limit anywhere between 12,000 and 60,000. Those are much larger ships really, and the prices reflect that difference.