Dark basic, even 1.3 with no dark matter comes with a HECK of a lot of 3D modles for you to use, from aircrfat to characters to lamp posts to furniture to weapons. so you wont really need a 3D designe thingy staright away, get the codeing worked out first.
just for your information a the 2 best 3D packages you can get for FREE are
Milkshape 3D
GMAX (3d studio max's little brother)
Once you have been tweekign around with these for a while and got the 3D designe working for you, you can then think about shelling out some cash for one.