Work Mithrel is level 15, x2pp is a general III, also level 15 an Slay Orcs requires a Weapon IV, level 25.
Base Cost for an item is (total levels of all spells required to make item) x (time in weeks needed to create item) = gp cost.
Selling price can be additionally multiplied by level of alchemist, though I ignore this rule.
Section 9.0 of TC covers cost. The big change for me is I altered weeks to days in contruction time. I also only require one Make or Work spell.
So, a mithrel sword takes 15 days to make (15 weeks by RAW). Adding Orc Slaying requires another 25 days, and adding the x2pp requires 30 additional days (each additional enchantment increases time to construct by x2. Adding another level 15 enchantment would require an additional 45 days...again, weeks by RAW).
So 70 days at 8hrs of work a day and 55pp's per day. No small understaking. The cost would be total level of spells (55) multiplies by time to make (70) or 3850gp. By RAW, since this requires a Guild master level Alchemist to produce, the selling price is 8x base cost, or 30800gp. At 1/4 ounce coins, thats 481.25 POUNDS of gold. A rediculous ammount to be sure. Without the multiplaction in selling cost, it is still a solid 60 lbs of gold, enough gold in RM to live very comfortably on for 100 years. I assume cost to construct is 60% of base cost, the rest is profit. If using the GM Law sale/resale tables, this balances very nicely.