Autumn would be the time to try. What kind of company would move a 25-foot tree for five hundred dollars? It seems like an extremely low price, unless the two trees are thin sticks. By the way, they are very tall trees in terms of transplant size. Since we have no idea how close these trees are growing close to each other, it's hard to say if this is true or not.
Established tree root systems can have an extensive extension, far beyond the drip line in most cases, often equal to twice or triple the height of the tree. If you are close enough for the trees to touch the canopy, you can bet that there is a serious mixing of the root systems and even removing a fairly compact root ball by a tree shovel would likely damage the root system of the remaining trees. Exactly how much damage and how recoverable is under discussion. By the way, the above-mentioned root pruning is not a bad idea to remove trees (but not long ago for the remaining trees), but it usually takes much more than 8 weeks to successfully achieve it.
In general, the recommendation would be to trench or prune roots in early fall for a spring transplant or with even older and more established trees (such as OPs), up to one year before the contemplated move. Although transplanting is a difficult and often expensive process, it can be very rewarding for those who are passionate about gardening. But how much does it cost to relocate a tree? And who the hell can do it? Well, the answer to the last question is at least one certified arborist. None could be moved with a shovel and the company's founder had planted them, so the company was willing to bear the expense of having them relocated during the expansion of his office.
So how much does it cost to transplant a tree? Keep reading to find out what factors are included in an estimate.