I have patiently awaited an EQ5 GOTO Upgrade kit for well over 2 months now, after being accidentally supplied an EQ3 instead. I contacted ALL Australian retailers of these, with prices ranging from a low of $525 to a high of $800, and yet only ONE of these retailers had any in stock (naturally, the $800 retailer). Tasco initially said early May, then LATE May, now they aren't saying, so...
Got onto teleskop-express, and they too are out of the EQ5 upgrade kits (though their price is REALLY good even after delivery cheaper than every Aussie retailer), SO...
I went with the iOptron GOTO Nova kit as recommended me by a couple of guys. Even cheaper than the Synta product, it came in at $448, including delivery! OK, not sure what, if ANY warranty I will get (though believe iOptron is VERY good with it), but saving THAT much is just seductive, meaning I can spend more on other astro gear

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My only concern is Teleskop Express says it HAS the ST4 converter, whereas iOptron-USA's page says it NEEDS the converter. Bought one just in case