This app was mentioned in 2 comments, with an average of 1.00 upvote
That depends if you mean "regularly cheaper" or "once in a while spectacular finds".
Shouldn't the bigger question be: where will you get power when the battery runs out?
I've been using computers for 30+ years. Never saw an android tablet app for what you want. There are some PC gardening apps though. Just books. The most valuable assets for camping, gardening and such is knowledge and experience.
Here are some apps you might find useful, for android devices: