I am not sure of why you would not want side imaging unless you are just dead set on getting the cheapest model available. A 7″ model with side imaging would be considered small and harder to see fish then on a larger model. But rocks and weeds (weed edge) surely standout well even on a 7″ side imaging screen and would be easier to see/find than with just 2d or di.
The Helix is a good model but I would suggest going with the Garmin Echomap series instead. The touch screen of the Echomap is just easier and friendlier to use then the Helix. Also the Echomap comes preloaded with lake maps and you would not have the added cost of buying Humminbird maps. If you fish multiple areas then the Hummingbird MN, Lake of the Woods, Wisconsin and Dakota maps all start to add up and get a bit expensive.
The Garmin Striker series is even less expensive and has the preloaded lake maps but I do not believe that it is touch screen.
Even when comparing the exact same model the prices vary drastically from one place to another as well as varies throughout the year. Shop around and I would not hesitate to purchase last years model unless you may desire a specific new feature.
If you are going to Cabelas then they surely can point out the differences. I would not purchase from Cabelas at the store unless you checked pricing at other sellers for the model desired. You can always order it online from Cabelas later in the week if you find their pricing is good and get free shipping.