Caveat: OP, sorry if the following is no longer beneficial as I see it's been some time since you posted. However, in the case you never found info of worth and for anyone who searches and upon your thread, as I just did, I submit the following.

I too used Shopsavvy almost exclusively but as it's usefulness faded and, as I became more aware of other variabilities in price comparison that makes it a little more difficult to simply scan to get the best price, I don't use one tool anymore but many.

For the scope of this thread, I'm going to simplify what I've found down to just "on the go" mobile app tools and not getting into cash back from certain credit cards which can factor into this; having a credit card, with a 60 day price protection tool will make you a little more sane about this process which can result in anything but especially when you wander hours later from the "rabbit hole" from a simple purchase with only a few dollars saved or, what's frequently the case for me, not having bought it at all lol (•‿•).

I first will use Shopsavvy because it includes many stores plus by scanning the UPC , it provides extra information about the exact model which can come in useful later. If it's a larger purchase and the results from Shopsavvy seem off, then I'll search the Slickdeals forum app. If there seems to be very little posts or none that show any dramatic price differences, I'll search Amazon (not necessarily the best price but I prefer to buy from them because I rarely go to stores to shop so it's that much harder for me to make returns in which case Amazon's self shipping returns makes it preferable to me).

While Amazon is certainly not the guaranteed cheapest price in the game as they once were (especially pre internet sales tax days), they are very competitive and will often change the prices on their website to reflect other big websites' prices like Newegg or Walmart within a few hours of the difference being posted.

One of the best reasons to use Amazon as a price comparison tool, is not in the direct sense as one would typically approach these apps. It's due to a secondary service that using Amazon gives you access to, CamelCamelCamel.

This website is by far one of the richest sources of price information and seeing trends and the flux of prices over sometimes 3 years. The price changes will often tell you enough as to whether it's a "good enough" or if you can wait and do better. While CamelCamelCamel.com is not technically an app nor has an official app, although you could use Hermit Lite or one of the other app cloners and make the website your own semi custom app, there's altetnatives to make this whole insane thing that we put our selves through a little more quick to wit I personally use TryCamel.

Essentially, once you install it, you will have it as an option under the share Amazon link and it will do the rest for you.

Finally, for larger purchases or something you have a little more time to explore, eBay's advanced search for completed/sold auctions is one of the best, free, long standing little known tools for buying decisions.