market value of my gears

Just in case your are serious here is a link to the Orion bluebook. It is a service that you will have to pay to use. Also, as has been previously mentioned, conditon and original packing and manuals will also have a lot to do with the values of these amps, but this will give you some idea of worth.

If you are in Hong Kong that is where you should be checking prices because that is where your equipment will end up anyway. Besides, the prices will be higher there.

That old crap's no longer worth anything. As a favor, I'll take it off your hands to dispose of it. And, as a sign of generosity will even pay the shipping here to me.

There are examples of the Marantz and Jadis models that are up for sale (or auction in the case of the 8B) here at Audiogon right now, so you can see what people are asking for them.

Your JA200 is considerably older than the one being offered, which should be taken into account in determining your asking price.

The McIntosh 225 and 240 are not especially rare, so I suspect that a little Googling would turn up recent asking prices.

I don't think I've ever seen an MC3500 offered for sale, but fwiw a 2012 valuation of $12K is cited in this reference. Not sure if that is for one or for a pair, though :-)

Regarding the Orion bluebook which was suggested above, I have no knowledge of how realistic their current valuations are for vintage tube gear. But I can tell you that the 1991 bluebook which I have absurdly undervalued most examples of collectable vintage tube equipment, relative to their true worth at that time.

All of them in mint and original conditions.

Keep in mind that the value of classic vintage tube equipment such as this is extremely sensitive to cosmetic condition. Very little equipment from the 1960s or thereabouts is truly mint. Any minor scratches, speckling of chrome, discoloration, etc., will reduce value considerably. If the serial numbers of the 9s are not close, that will reduce value somewhat. If one of them is the blue chassis version and the other the brown chassis version (as opposed to both being the same color), that will mean $thousands off.

Finally, willingness to ship internationally can make a considerable difference in how much pieces like this will bring.

Good luck!
-- Al

Audiogon Bluebook prices are based on the average of actual sales, and often seems pretty close to what I see a lot of used equipment selling for. Original Marantz 9's for example are listed at well in excess of $6,000.00, certainly not lowball.