on whether or not to really take the tour for getting the hotel at that particular price and find you may not want go on ahead with it, you can usually find a hotel for just a little bit over that same amount for 4 nights on some sites that sometimes run specials depending upon the hotel. Like what was mentioned before, others have had great success with Priceline if want to go that route.
The site
www.go2orlando.com in the past has offered a few properties that may be in that range and not that much over what you would be paying; also check out
www.floridakiss.com for offerings or
www.hotelkingdom.com.
Also, since you said you are doing only WDW this time (assume you are referring to just the Magic Kingdom park), you will have more time on your hands as supposed to if you were visiting the whole entire complex.
So I think you would be o.k. in structuring your overall vacation time if you wanted to take at least just one tour out of five days to get the tickets (saving some money) especially if this is definitely a budget trip and you want to have more money left for other things like buying souvenirs, eating at different restaurants, snacks, or other misc. items.
In the past, my family had attended one tour for a resort to get discounted tickets quite some time back and we were down for 5 nights (which is only one night longer than you) and the whole presentation lasted for about 2 hours and it was not at all a burden on our time (and we even visited 3 parks and saw other attractions/shopped too).
After touring and during the sales pitch we very firmly and clearly stated in a polite as well as friendly tone that we weren't interested in buying then proceeded to get up and exit. However, some sales people from what I have read can come off as being pushy and a bit intimidating at some point so if you think you will be able to stand your ground and not be pressured into giving in if you are not interested.....and walk away, I think it will work out fine.
Another thing, would be to get a rough estimate of the tour times along with an approximate time of how long they will last because they can vary (and may run over) so take that into account also; maybe deciding whether it would work out best either in the morning or afternoon for whatever you might have planned for later on.
Also, if there happens to be an activity scheduled right afterwards in an event the person seemingly is not accepting no for an answer and it becomes evident that you are not interested in purchasing, you can communicate your family has a pressing engagement and have to leave. I would be sure and thank the sales person for their time at the end and let them know if for whatever reason you change your mind at a later stage (like if you have thought about it in more depth once arriving home) you will be in contact with their office.
Hope this helps/good luck with whatever your decision; have a great time!