By RAW:

Spell effect, once per day, command word activation = spell level x caster level x 1,800 gp / 5
Material component costs are multiplied by 50, total is 1,000 gp + 4,000 gp for dimensional anchor rider x50

When adding an additional effect to an item, each additional effect costs 50% more. Therefore add 50% to the cost of an item of Dimensional Anchor.
Spell level x caster level x 1,800 gp / 5 x 1.5

Thus we end up with:

Hallow: (5 x 9 x 1,8000 / 5) + (1,000 + 4,000) x 50
Total: 266,200 gp

Dimensional Anchor: 4 x 7 x 1,800 / 5 x 1.5
Total: 15,120 gp

Total item cost: 281,320 gp by RAW.

Note that this is completely debatable based on what you interpret the actual benefits to be. For example a similar item, the Darkskull, creates a permanent Unhallow effect for only 60,000 gp.