You can get those Cuffs in game from an NPC shop (mayan shop for 360g). (use search) no need to waste your credits on something like that. Best to save it up till you can get maybe a -80 weight from the credit mall instead.

Here is the - SPD list. Maybe it may help. just mouse over each Item and you can tell where to get it. If it says Mall then its from mall. If it says a Shop then go to that shop. If it says nothing then you need to compound that item.

Iron balls, Shot puts and Stone balls you can get from Peaches. Ask some people in your guild/world/friend list to perhaps help you get 1 or 2 or 4.

With luck you may also find some tossed away on the ground in welling or SB after 15round on Friday nights, Or sold for under 5k in someone's shop.

THIS MAY BE MORE IMPORTANT AND HELP
You don't need 0 spd to burst as long as your spd is under 40 or 30 you can still combo with he cow or sheep.

Its your water that also determines if you combo as well. So get your Water OVER 100 spd (with stat or items) and then your team will begin to combo