The biggest mistake that newbies make when trying to purchase DeFi funds like Sphere Finance, is that they purchase Eth or another coin on the Ethereum network and then try to swap/bridge it for the new token and pay high gas fees. The best way to avoid these high gas fees on the Ethereum network, is to stay off of it and try to do your transactions on networks with low gas fees like Polygon, Avalanche, etc.
For instructions on how to purchase tokens in Coinbase without paying high gas fees, check out my recent blog article here.
Once you’ve got your token (e.g. AVAX) on a low gas fee network like Avalanche, you can use a bridging site to bridge that token’s value from the source network (e.g. Avalanche) to the new token (e.g. Sphere) on the destination network (e.g. Polygon).
Sphere has partnered with Rubic to make the bridge/swap extremely easy and the fees are relatively low. Simply click this link to access Rubic. You will need to connect your wallet. You will need to set your source token and leave the destination token as Sphere on the Polygon network.
Please note that with tokens like Sphere, you will need to adjust the Slippage to ~15% in order to pay the 13% deposit fee and 2% of price slippage.