Hello, this probably is a late reply
but better than none
Talking about Delkevic swingarm and wheels set, it is the main recipe for Indonesian Ninja 250/300 modification, around 60% of member in my Ninja250 Community in my town apply Delkevic sets on their bike
Costs us around
$200 - swing arm (up to 6.0)
$350 - front 3.5 inches and read 5.5 inches wheels
$250 - 120/60 and 180/55 tyres
bigger rear sprocket is recommended, since changing swing arm and bigger wheel and tire might add some weight. Just add $100 for sprox and chain
Delkevic bigger wheels set is the most popular product in my country, can be easily found in local motorcycle mods shop, the mechanics on the shop would install those parts for you, and you could just sit down, relax while drinking iced tea.
Talking about the payment, yes it's going to be difficult because they are using local bank transfer method instead of Paypal, and sorry to say, I'm quite familiar with the shop you showed on above pic, it's a little bit overpriced, but if you're okay with that then it's a green light for ya. You might want to try to contact "MotoChief" which the contact can be found on Instagram (just search motochief) and send a direct message. Indonesian shops are not familiar with websites, mainly because it's not free, and social media like Instagram can be accessed easily and freely by Indonesian.
I'm telling you, Asia (especially Thai and Indonesia) is your motorcycle mods heaven, trust me