There is a cornucopia of fine guns out there. BV1(Boss, H&H, Purdey, and Woodward)-OQ1(best grade SLE, but not extra finish)-CC1(pristine/best of 50) = $40,000 USA retail for a 12 gauge SXS of 1890ish to 1960ish vintage. BV2 is 3/4 this amount, BV3 is 1/2, and BV4 is 1/4. You can cut the price 2/3 to 3/4 by easing back on the Current Condition level. And, there are some very nice guns in "A" and "B" grades, also.
Above said, $100K will buy 3 to 5 very nice older guns. Or, the whole wad could easily be spent on one modern bespoke gun. A modern bespoke BLE, even a pair, could leave a good deal of wiggle room for future purchases. There are far too many ways to approach this to nail down one as "The" way.
