As Slohairt has already pointed out, having a fine quality kilt in your family tartan doesn't have to be as expensive as some perceive. You said in your original post that the MacLellan tartan isn't common and so would have to be custom woven. Not so. Lochcarron and House of Edgar both stock this tartan.

If you are interested in a hand sewn 8 yard kilt, the Scottish Tartans Museum offers the MacLellan tartan in 13 oz for $479 and 16 oz for $499.

If you want a less expensive option, there is always a four yard box pleated, which will set you back $395. Or for an expensive option you can go with a machine stitched "casual" kilt in the same tartan for $290 or $299 (medium or heavy weight).

Those are our prices and should be comparable to other kilts of the same quality offered by others. But my point here is mainly that this particular tartan isn't a custom weave and so your kilt may not cost as much as you first had in mind.