Insider tips usually come from people that live in the community. Get up and go to the bus stop in the morning and talk to the Moms or find a garage sale in the area and go talk to them. Go to the schools that feed from these areas and find folks that live there. Talk to lots of people that live there.
I highly advise you to get independent appraisals before making offers. Prices all over the country are moving targets right now. If you can afford it, do it. Ask your Realtors for several experienced real estate appraisers. I would go with an older established company that keeps all sales transactions on record especially private sales. They are usually taken over by a family member and passed on from generation to generation.
The online tools on the Internet are no longer able to calculate accurate appraisals. You must have a reliable Realtor or an Appraiser. A reliable Realtor will give you a credible market analysis. No one can predict the future in absolutes. Also ask to see the current competition.
The lenders have an appraisal software system. It tends to appraise on the low side. There is nothing that can replace a full appraisal.
I think your "trending" question is better to ask an appraiser. We as Realtors have access to trending information on our listings but I do not know if you have the same access. We also have access to predicted trends through the National Association of Realtors but again they are predictions not absolutes.
Appraisals have gone up in cost in Florida where I am and I expect in NY too. We are averaging $400 per appraisal in north Florida now. I would guess yours is $500 to $800 or more and will be based on the size and type of property. The bigger the house or investment property, the bigger the charge.