Yeah, unless you luck into one, the days of "cheap" 98k's are way over, with RC's now hitting $800 plus on GB....which to me is ridiculous...I wouldn't buy an RC for $400 much less what they are now hitting....I only own one, and it is my LSR sniper repro....there is only one other RC I actually kick myself for not grabbing, and it was a WWI Gew 98 that had been converted to 98k standards...
There are good ones out there, a buddy of mine picked up an all matching byf 44 at the last DACA show for $800, he decided to sell it to me, I got it for $1000, which is probably less than half actual value.
Of course the ultimate to look for is one with all matching numbers....parts will be serialed with at least the last two digits of the s/n...early ones up to about 1940 had virtually every part serialed, then things started falling off, until by late war when only major parts were serialed.
It is a minefield though...tons of fakers out there turning non-matching gun into matching. They will border on laughably easy to spot, to very difficult. Very well done fakes can usually only be spotted by looking for fine differences in fonts, or by seeing something that is not typically "correct" for that particular maker and time period. For example, certain dot's had the serial number stamped on the bottom of the rear band for a certain time period, if you find one that has a serial number stamped in the normal location, its a red flag to check over everything carefully.
Sometimes it is relatively easy to see the grinding done to remove an old serial number, and re-stamp...but a lot of guys stocked up on later war unmarked parts (like barrel bands) and simply stamp them to match, especially on "rescued sporters" which is typical of bring backs who have had their stocks cut down. they lose the front end of the stock, handguard, and bands typically. To restore to original military configuration, you just need a stock, handguard and bands. Back in the 80's and 90's when 98k's were plentiful, enterprising guys could easily get the parts and restore them. Some went out of their way to find un-numbered parts, and then either put them on as is, or stamp matching numbers into them. Now these are selling as original matching guns, or "armorer repair" guns....again, you have to be very familiar with how an original should look as far as serial placements and fonts, or looking for the telltale signs of an actual depot rework, or the markings that would be on original armorer replacement parts...
When run of the mill all matching guns can fetch over $3000 on GB, there is lots of incentive for humpers to do their thing and turn a $600 gun into a fake $3000 gun...
If you are just looking for a shooter, at this point finding an RC is the best bet...but as I said, even they tend not to be cheap...or scour local gunshows...unfortunately usually anything good put out cheap will be scarfed Friday during set up, or Saturday morning...like the byf I just got, my buddy found it Friday during set up...the one show I missed because I had to head to Bermuda for a job...