I have already established a SD IRA with a custodian.I am looking at establishing a SD solo 401k with checkbook control with a provider at lower costs.I also am looking for advice if it is smart to leave my SD IRA with a custodian and pay the higher fees or if I should roll it over to a provider to minimize cost and gain checkbook control.Thank you.

Can be severe penalties just like city STR restrictions, maybe $100s/day and legal expenses to force compliance. 

Is it astronomically expensive? 

It is better to create a separate bank account just for your rental activities.The reason is that it will be easier for you to recognize what is income / expenses more easily.

From there it's point and click categorizing and tagging of income/expenses to their respective properties. 

On the other hand, if you have a lower budget, let’s say $100-$150k.

.- Get a property subject to where you take over payments for a loan with lower interestfeel free to reach out and discuss some ideas

More specifically, it requires (like all REI) a solid understanding of the operational expenses and local market.

It has much lower interest rates than a HELOC and comes with some additional unique benefits.

For example: 10% of profits during ownership, and then a 20% profit share on the sale if a certain sales price is reached, maybe 15% if a lower price is achieved etc.