G'day, is there any possible way of stretching the budget to this which is the perfect starter scope? I realise it's twice as expensive but it will be worth it and you and your son will appreciate it. The telescope in your link looks to be very fiddly to use. If you're interested ask the seller to post you a photo of inside the tube (i.e. the primary or main mirror).
http://www.ebay.com.au/itm/DOBSONIAN...a8d275a&_uhb=1
It will be waaaaaay easier for you and your son to use and you'll see heaps more in a shorter amount of time than what you will with the telescope in your post. Comes with superior eyepieces and collimation tools too - i.e. all ready to go. Any questions just ask
Regards, John.