We went with Kimberley Wild Expeditions, James was our guide. I believe he is one of the owners and doesn't always guide this tour. He was probably the best guide I've ever had, I learnt so much without feeling like I had been 'talked at' all day. He has an easy going, friendly, trustworthy manner.
I agree $300 is a lot for a day tour, but it was worth it for me. I would love to have done their 2 day Kimberley Gorges tour, to experience the night and then see the sunrise over the desert and spending longer covering a similar distance are probably the main things that would improve on the tour we did.
I just read some of the reviews on Tripadvisor and the couple that rate the tours as terrible have a point - it is a long day, with lots of bouncing on unsealed, dusty, bumpy roads and we covered over 800km on the day, but we knew that would be the case. The drive was part of the experience, I let them know in advance that I suffer from slight travel sickness and requested a seat at the front of the bus which was all I needed along with ginger tablets to avoid any nausea. Everyone on our tour seemed to have a great day, even the 4 children (approx 10-12yrs old).
I loved the tour and have no problem recommending kimberleywild.com.au