Hello, and welcome back!
One way to price pets is using the creatu search under the Information tab. Following is an example of how to set it out:
Location: Rancher Shops
Species: Mirabilis
Color: Cream
You can leave Effect, Mutant and Gender set to Any. In the boxes on the right-hand side, you can ignore all of them except for Price, where you want to put 1 in the left one and leave the right one blank.
Options:
Order by: Price
Direction: Ascending
However some pets don't stock very often in shops so the prices may not be accurate. It's often a good idea to compare the results with prices for other species.
Personally, I'd suggest around 500k (500,000tu) for the cream would be fair, and 15mil for the blonde.
The two pets you're referring to are Haberisar and Saruka. I just checked and it doesn't look like you have either of them on your account though, so you must've given them away or sold them :( There are some for sale though, so you could use the creatu search to find the cheapest ones.
Let me know if you have any other questions and I'll do my best to help c: