Yeah you don't need to buy a massive inbound channel. The only reason to do that is if you expect to be receiving significantly more than you spend. In which case boltz.exchange or other solutions to empty your channels are a better deal.
Discussion
I bought the 500k inbound channel for 15k sats, and sent 200k sats to the channel giving me 200k outbound capacity against a remaining 300k inbound. That's been pretty solid for me. It's been running great for the past two and a half months.