Despite what some growers seem to thing bigger base is not always better for bonsai.
Aesthetics play a huge part in good bonsai. Trunk taper is very important and many, maybe even most?, huge trident trunks have either no taper, reverse taper or just plain ugly taper. You can grow new branches in just a few years but taper is much harder to remedy.
Check amongst all those leaves to see if nebari is consistent and in proportion. Around branches and previous chops are usually the worst places.
Nebari is another big factor in good bonsai, especially with maples. While nebari can be modified it will take 5 years or more for the new roots to match a larger trunk. If the trunk just needs a couple of new roots I'd consider it but if the whale nebari needs replacing it may not be worth the time and effort.
This tree looks quite tall for the trunk thickness. 30" is tall for 4" base. Would you pay that money for a thick base but then make a tall, thin looking tree? Plan to shorten the trunk? Make sure there is a good place to make a trunk chop. Behind an existing upward branch or sub-trunk if possible. Large chops can heal over quite fast while the tree is growing fast but in the final stages while growing branches and refining you'll need to reduce growth so chops now take many more years to heal. That may not be an issue if the cut is hidden behind so check for suitable chop sites.
Maybe make a blind chop and start the top of the tree again? Allow many years to grow a new apex to match the base. The thicker the base the more years the new leader will need to catch up. Then add more years for subsequent chops to continue taper and build branches.
Value is uniquely individual. You'll need to make that call but just be aware of all the ramifications and don't be seduced by thick is good. Bonsai development does not occur overnight.
My eyes were bigger than I realized! Went with this one instead for about a third of the price. Got some great movement some nice basal root flare under the dirt. Flaky bark!
Looks like a much better choice to me. Well done.