Ive been pouring through the Files on freelancer and i think i found a way to edit the Ship Market.

Use BINIQDU(which i find to be the best current edtitor) and edit the file Market_ships.ini

The Base Value is quite complicated i usually try to use the Capital Planets of the houses in all my editing for my Ship Market Mods.

For Example
Li01_01_base (Manhatten)
Br01_01_base (New London)
Ku01_01_base (New Tokyo)
Rh01_01_base (New Berlin)

Now for the Interesting Part the ships activated for this base have these values.
Ill break them down.

market = Ship Package, Player Class #, -1, 1, 1, 0, 1, 1 (Ship available)
market = Ship Package, Player Class #, -1, 0, 0, 1, 1, 1 (Ship unavailable)

And the Ship Package names are kindof hard to pin down, for example.

bwf_package = Border worlds light fighter
bwe_package = Border worlds heavy fighter
bwe2_package = Border worlds very heavy fighter
bwfr_package = Border worlds Freighter

[BaseGood
base = Li01_01_base (Base Value)
marketgood = gf1_package, 0, -1, 0, 0, 1, 1, 1 (This Ship is not available)
marketgood = gf2_package, 4, -1, 1, 1, 0, 1, 1 (This Ship is available)
marketgood = gf4_package, 13, -1, 0, 0, 1, 1, 1
marketgood = gf5_package, 24, -1, 0, 0, 1, 1, 1
marketgood = gf6_package, 30, -1, 0, 0, 1, 1, 1
marketgood = bwf_package, 4, -1, 0, 0, 1, 1, 1
marketgood = bwe_package, 20, -1, 0, 0, 1, 1, 1
marketgood = bwe2_package, 1, -1, 1, 1, 0, 1, 1
marketgood = bwfr_package, 10, -1, 0, 0, 1, 1, 1
marketgood = cof_package, 8, -1, 0, 0, 1, 1, 1
marketgood = coe_package, 28, -1, 0, 0, 1, 1, 1
marketgood = coe2_package, 32, -1, 0, 0, 1, 1, 1
marketgood = lf_package, 1, -1, 1, 1, 0, 1, 1
marketgood = le_package, 2, -1, 0, 0, 1, 1, 1
marketgood = lfr_package, 1, -1, 1, 1, 0, 1, 1
marketgood = bf_package, 6, -1, 0, 0, 1, 1, 1
marketgood = be_package, 8, -1, 0, 0, 1, 1, 1
marketgood = bfr_package, 4, -1, 0, 0, 1, 1, 1
marketgood = kf_package, 10, -1, 0, 0, 1, 1, 1
marketgood = ke_package, 13, -1, 0, 0, 1, 1, 1
marketgood = kfr_package, 10, -1, 0, 0, 1, 1, 1
marketgood = rf_package, 20, -1, 0, 0, 1, 1, 1
marketgood = re_package, 22, -1, 0, 0, 1, 1, 1
marketgood = rfr_package, 20, -1, 0, 0, 1, 1, 1
marketgood = pf_package, 2, -1, 0, 0, 1, 1, 1
marketgood = pe_package, 13, -1, 0, 0, 1, 1, 1
marketgood = pfr_package, 4, -1, 0, 0, 1, 1, 1
marketgood = bhf_package, 4, -1, 0, 0, 1, 1, 1
marketgood = bhe_package, 13, -1, 0, 0, 1, 1, 1
marketgood = bhe2_package, 26, -1, 0, 0, 1, 1, 1
marketgood = oe_package, 16, -1, 0, 0, 1, 1, 1

And that is how it is go ahead and experiment with them.
Just remember that there is a limit how many ships a base can sell so when you add a ship you lose a ship.
A planet can have about 3 ships avaible.
A battleship only one.

Good luck

Sephiroth

P.S. Activate the Order Heavy fighter (marketgood = oe_package, 16, -1, 0, 0, 1, 1, 1) It costs almost nothing and its a good starter ship