On buying a less expensive bike for riding dirt trails - used and new

A friend asked me for advice on buying a bicycle suited to dirt trails (up to novice singletrack as well as city trails). She would want to spend under $1500 (preferably under $800!). See also: online sources and buying a used road bike.

The best choice for this is probably a hard fork mountain bike with 2" tires. These, however, do not exist short of very high end gravel bikes that are way overkill for her. The next best options are 

1. Hard fork fat bike with 4" tires and a less aggressive tread. This works reasonably well for shorter road trips, avoids all the cost and complexity associated with a quality front shock, and will be comfortable on any kind of sand and dirt and most novice trails. Alloy frame.
2. A "hard tail" (front but no rear suspension) mountain bike. Alloy frame.

Used or new?

Most used bikes are overpriced. Always compare to new and consider bike shop customer support. Don't buy used without an expert friend to inspect. A 1996-2010 26" wheel size hard form mountain bike with a quality front fork that still works can be a good deal. These are hard to find but often good value; sometimes they show up at community bike restore/sell shops and used bike dealers. Bicycle BlueBook helps with evaluating costs. Always compare to cost of new similar bike. Get help to avoid buying stolen bikes. Buying a used road bike is a bit dated but mostly still true.

A 1994 high end hard fork 26" mountain bike can be a good deal. Very hard to find. Consider calling Mr Micheals Reycles Bicycles and asking them to keep an eye open.

A disadvantage of older trail bikes is their "geometry". Modern trail bikes have been changed so they are much harder to go over the front wheel; older bikes are more responsive up front but sometimes that's a problem.

Bike shop employees sometimes sell 1yo bikes for what they paid for them (half-new) but these are usually high end bikes.

Mail order?

New bikes are considerably cheaper when ordered by mail but this is more for an expert buyer. Canyon is a well known name with a reasonable reputation. Their prices are typically 20-30% less than local retail. Bike shops may put Canyon bikes towards the back of their repair queue, understandably they favor bikes sold through shops esp their own customers.

Local Bike Shops

In the MSP metro area I've been happy with Freewheel, Erik's and REI. There are some other high end shops I like but they tend to be pricier.

Outfitters!

Outfitters that do mountain bike tours often recycle their fleet yearly. They buy on a discount and I think they sell for something close to what they paid. This can be a great bargain but the bikes go fast. I get an email every fall from Western Spirit giving me a chance to buy.

Some "reference" new bikes to use when shopping

I like Trek bikes. They are well made, well warranteed, easy to get parts for, easy to service locally, and are fairly priced.

1. Trek Roscoe 7 is a serious modern hard tail mountain bike. It's about $1,700 in April 2023. The Marlin 7 is their entry level bike and is also quite good at $1000. You can compare other brands (Giant, etc) to the Roscoe. 

2. If you decide you want full suspension for more comfort and easier control on rocky trails the Fuel EX 7 Gen 6 is a good reference, $3200 April 2023. Now you're out of the less expensive range. Omitting eBikes the top-line Trek Fuel is about $10K.

REI store brand bikes can also be a reasonable deal, but in practice most good bikes are very similar prices.