Managing/flipping several Instagram accounts (Questions)

In the near future, I am planning on purchasing several Instagram accounts and have heard that IG will suspend/flag accounts if there are more than 5 logins from one IP address. I am not using bots and will only login to each account several times (and make one or two posts) before re-selling them. How can protect myself from getting flagged/suspended? Would I be able to use a VPN or do I need to pay for a proxy service just to login/manage these accounts? Any help is appreciated, I am just trying to find the most cost effective method for my situation.

It depends on several factors such as how do you manage them (phones, emulator, software etc), the daily interactions, if the accounts are or not warmup and many other factors..
I should use 4g proxies or actual sim cards with mobile data for the accounts to have a better trust score, never vpn.

It isn't the proxies and sim only, actions matter too. Some people tend to escalate their action numbers to 500/day and this is where the problem starts. I generally keep them down to 50.

Using a cheap VPN/proxy can invite more trouble than using 7-8 accounts safely on the same device if you're not spamming.

Be careful, get different devices if possible or if you're going the proxy route, get the best 4G proxies possible to ensure they don't get stuck in the verification loop and avoid spamming if you don't know what you're doing.

You can use 4G mobile proxies, rotating ones will give you the ability to create at least 15 accounts under one IP subscription - you just need to rotate the IPs everytime you create an account.