Did you get these numbers from a dealer?
Please shop the trade-in value at multiple dealers. This value can be vary. I have seen 10k worth spread on trade-in value for a 50k car. Please submit your VIN to get the trade-in quote from these online dealers: List of places to sell or value your car online
Even though they may not buy your Audi lease, but at least you will get the baseline to ask for more money for your trade-in.
One more suggestion: May be, consider buying a brand where you won’t face the restriction to sell the lease. Having flexibility to sell your lease to any dealer is a real big advantage. You can exit anytime without waiting for the entire 3 yrs term plus you won’t be left at the mercy of Audi dealers.