True Paul,
The cheapest upgrade is weight loss...and all you have to do to make that happen is pedal...lots!!
I started at 100kg+ and a year later I was low 80kg range...200km a week and eat what you like...I guarantee you will loose weight!!
From being destroyed after 2km on the bike to finishing a 256km ride with just shy of 6000m of climbing.
Eventually you find you can go faster...and for longer...before you know it your competitive.
Although I have never raced, I hold my own with the B Grade bunch at Olympic Park...on a good day, I'm sure I could stay with the A Bunch for at least a few laps...all from recreational riding!!
My solo average speed went from 20kph to 34kph for an 80km ride on the M7 cycle path...all in just over 12 months.
Bunch training now see's an average speed of around 41kph for 25km.
If my 'never played sport in my life body' can get moving...anyone can do it!!
Just get out and get pedaling!! And stick with it!!
Cheers,
Phil.