I've upgraded my Pixel XL every year from the 6 to the 9 (pro). Say what you will about that financial decision. Each year I've told myself I only did it because it was such a "great deal" either for the sale price on the pixel or the "boosted trade-in value" from the previous.
I thought it would be fun to look at the prices for each in the context of the others and see how they varied from year to year.
Each year I bought the XL model with the lowest storage space (except the 9 pro), and pro when it was offered. Only one of the years I received a promotional item and I'll note that. The total price is listed with tax.
Pixel 6 Pro 128gb
10/19/2021
Total: $969
Trade-in: $175 (of two year old Pixel 4XL)
Pixel Buds A: $99 (retail)
Net: $695
Pixel 7 Pro 128gb
11/7/2022
Total: $968
Trade-in: $500
Net: $468
Pixel 8 Pro 128gb
12/26/2023
Total $753
Trade-in: $315
Net: $438
Pixel 9 Pro 256gb
11/6/2024
Total: $904 (with "gold" play points discount)
Trade-in: $699
Net: $205
Net (If I had bought the 128gb): ~$105
Originally I'd planned to keep my 8 pro another year, but looking at it this way it makes more sense why I couldn't help myself and go with the update again.
On another note, I find it annoying the way Google plays around with "boosted trade-in values." I get that they do a lot of sales to encourage purchases, but changing around the trade-in values to create a sense of urgency and price confusion -- especially on their own phones! -- seems distasteful to me. They should stick with what they think is the actual value of their phones, and admit whether they do or don't hold that value over time.
See the other comment chain, looks like you can still get the 30% off deal by signing up for Play Pass.