Trying To Nail Down Some Sales Forecasts, Help?

So I have just taken on a new telemarketer to help me out, so here is a rough breakdown of profit/loss for the future, I'd love any feedback on my maths/ideas/projections etc :

1 Sale Per Week
Est 600 Calls Made
Est 5% Leads = 30 Leads per week
Est 4% Conversion = 1 Sale per week
$1657 - (Phones $36, SEO Guy $150, Google Local $100, Telemarketer $200 (Commission = $331), Web Designer $200, Hosting $38, Tools $144 = $1199 ) = $458 net per week.
Expenses = $1199
Gross Profit = $1657
Net Profit = $458

Earning $22 000 per year net profit

2 Sales Per Week
Est 600 Calls Made
Est 5% Leads = 30 Leads per week
Est 8% Conversion = 2 Sales per week
$3314 - (Phones $36, SEO Guy $150, Google Local $100, Telemarketer $200 (Commission = $662), Web Designer $200, Hosting $38, Tools $144 = $1530 ) = $1784 net per week.
Expenses = $1530
Gross Profit = $3314
Net Profit = $1784

Earning $86 000 per year net profit

3 Sales Per Week
Est 600 Calls Made
Est 5% Leads = 30 Leads per week
Est 12% Conversion = 3 Sales per week
$4971 - (Phones $36, SEO Guy $150, Google Local $100, Telemarketer $200 (Commission = $993), Web Designer $200, Hosting $38, Tools $144 = $1861 ) = $1036 net profit per week.
Expenses = $1861
Gross Profit = $4971
Net Profit = $3110

Earning $150 000 per year net profit

I'd like any critique of anything here, including anything I might have missed, since I have never been a maths guy!

It freaks me out how much more 1 more sale per week can do for profitability, from $22k per year to $85k? I probably missed something here that's embarrassing LOL so feel free to point it out.