Ian Callen is probably the only person in Australia with the skills, experience and equipment to do the job properly, so you might want to take some photos and get them over to him. Hopefully the trees have been well maintained over 20 years, if not their values will be limited. But of course, Ian's got a whole plantation of his own trees so the economics of taking yours may not stack up.
If you fancy giving it a go yourself, do. It's fun and lots of cricket people will be interested to support. I strongly recommend you just start with 1 tree, in order to work out the steps and avoid wasting too much wood. Felling and splitting are straightforward, sawing to shape can be done by a local sawmill. I can get you the dimensions if you need. The most difficult bit is accurate drying, unless you can find someone with a decent kiln. The clefts will air dry in 6 to 8 months, but the bats are likely to be quite heavy as it's hard to get the moisture out from the middle.
There's some posts in here detailing my amateur efforts and more photos and stuff in my Facebook page if you're interested.
Best of luck. Let me know if you have questions and I'll do my best to help.