Hello!
I tried to check recently sold listings for this card but there doesn’t seem to have been a public sale since September (according to pokemon price).I found this thread from back in June where the estimated price seemed to be somewhere between 5k and 7k but have the feeling that with the recent price increases for early WOTC cards this might be outdated.
Does anyone have a guess as to what this card might go for in the current market?
Hard to put a price on anything in this market, but I’d say easily above $10K. Maybe on a good day $15K+ in a big auction/pwcc.
A good thing to do would be look at the price differential between Base 2 and base set. From my experience, they have always been quite correlated. If you can establish a general expectation (eg, Base 2 usually sells for 70% of base set price), you can then pitch this against all the PSA 10 base set unlim zards that have been hitting the market 
. It’s not a perfect science, but it should give you a rough idea.
I would have to agree with @poken00b88, I think it would have to be a low 5 figure card now!
Thank you both!
So based on this (and incase anyone else is interested) the following is the average sold price for psa 10 unlimited and psa 10 Base 2 Charizards during five time periods.
The time periods that I selected were ones in which there were a decent number of sales of the Base 2 Charizard in the hopes of getting a more accurate rough value. All price data is sourced from Pokemon Price.
May 4, 2020 - Sept. 7, 2020:
Unlimited: $6171.97
Base 2: $5940.00
Difference: 96.24%
Nov. 11, 2019 - Feb. 2, 2019:
Unlimited: $1696.43
Base 2: $1417.18
Difference: 83.54%
May 4, 2018 - Sept. 28, 2018:
Unlimited: $1330.16
Base 2: $889.50
Difference: 66.87%
Dec. 23, 2017 - May 2, 2018:
Unlimited: $1520.57
Base 2: $1093.67
Difference: 71.93%
May 19, 2017 - July 29, 2017:
Unlimited: $1029.51
Base 2: $616.69
Difference: 59.90%
Based on this it seems that @chickenpalma , was pretty much dead on with the guess of 70% (the average difference before the spike being 70.56%)
If you take into account the current price of the psa 10 unlimited Charizard that is being auctioned by PWCC ($35,100) then the average for the unlimited zard goes up to $8238.30 which would put the difference inline with the historical average at 72.1%.
TLDR: If the historical price relationship between the Base 2 and Unlimited psa 10 zard holds and the Unlimited zard sells for 35k then the best guess at a current price range for Base 2 psa 10 Charizard would be between 15k and 24k (43% and 70% of cost of unlim.)
Just wanted to update the price estimate since the PWCC auction ended at 30k instead of 35k.
Rough estimate/range would be between 12.9k and 21k if historical price relationship holds.