Typing program alternative to Mavis Beacon for Mac

We are setting up a new iMac computer which is a switch from a PC, and are switching all of our files over, saving to external hard drive, etc. I think we will eventually (likely months down the road) set up our current PC for the children to use for all of their schooling needs, but in the interim, we need a solution for typing. 

Our thought was to purchase the Mavis Beacon software that is Mac compatible, but I was wondering if there’s a different/better typing program that you all have used with Macs. Christie? Anyone else?

I tend to buy programs/books/curriculum I really like and then don’t ever familiarize myself with other good stuff on the market. Before we buy the Mac-compatible MB software, I’d like to become more familiar with what some other good alternatives might be. We’ve looked at http://www.typingweb.com as an option. It’s a one-time $15 fee and is online-based. But what else is there? 

Ds is almost 10 and needs improvement in his typing. He currently types about 12 wpm. Dd is 8.5 and is a bit slower, but this is also her first year of typing. He’s been typing for two years, and isn’t making tremendous progress; hence my reason for wanting to explore other options.

Thanks so much!

Lindsey