MarineLand's are decent. My LFS likes them and they've never steered me wrong, so
Is the price of $560 for just the tank? Online they go for $3000-$4000 depending on the lighting they with come and stand and canopy, plus $600-1000S&H.
You're better off with a new tank.
That being said, my last tank and my current are both used tanks. My 155 was previously a freshwater setup. I hosed it out, scrubbed with water/vinegar mixture, hosed again, and then scrubbed twice with saltwater. I've had no issues.
If you buy a used tank, make the seller fill it with water. If they won't, make them drop the price. A tank that leaks can be fixed, but shouldn't cost as much money (obviously).
Farming pods is possible, quite easy. Just pick up a 10G tank, a very gentle pump, some live rock rubble and live sand. I'm pretty sure this site sells pods, dump them in, feed them, wait a couple weeks and you'll be good.
I personally have found it much easier to just spot feed and seed the tank by adding copepods weekly. So far, so good. My mandarin never took to the frozen food training and most that do, don't live as long from what I've seen. Most LFS's will sell Tigger Pods, a bottle of those every other week while the mandarin is young, and every week when they're older and you're good.
Forget about the Catalina Goby if you want a reef tank. They require cooler tanks than most fish/corals and really need their own special tank for this reason.
DO NOT PUT A SIXLINE AND A MANDARIN TOGETHER. I had a sixline kill a mandarin, I just read a thread on here today of a guy who's sixline beat up a mandarin and shredded its fins, etc. Sixlines cause chaos, they're just not worth it and they're impossible to catch once they are introduced to your tank. Save yourself the headache, there are much nicer wrasses.
Your fish list looks good other than that. Keep in mind that you can only have one blenny in your tank and one mandarin.
In a 125 Reef tank with fish here's what I'd do:
1 Mandarin (after at least 6 months of the tank up and running and at least 100lbs of rock with seeding the tank)
2 Clownfish (you really can have any two you want. Maroons are meaner)
1 Lawnmower Blenny - wait until your tank is 2-3 months old and you may have to supplement it's diet with algae sheets if your tank is too clean
1 Shrimp Goby (have you decided what type you like?) I personally love the yellow watchman
1 Royal Gramma
1 Tang of some sort (Sailfin or Kole or Yellow or Hippo)
2-3 Cardinals or Lyretail Anthias Females
Clean up crew:
5-15 Nassarius snails
5-10 Astrea snails
5-10 Trochus snails
10 Cerith snails
10 hermits (don't get hung up on what type they are, they'll die eventually, or kill each other for their shells so don't spend a ton of money on "pretty" ones)
2 Skunk Cleaner Shrimp
3-4 Peppermint Shrimp
2-3 Emerald Crabs
40 Gallon Sump - I don't run a refugium, but you absolutely can and should if you don't want to seed your tank.
I highly recommend a ASM G3 Protein Skimmer.
What lighting comes stock with the tank at your LFS?