Have a look in the For Sale section. There's an EBS Session 60 in there that fits your budget and I would think it fits your requirements. With the auxiliary input you can play music from an external source and jam along on bass which is great if you're starting out. I have no connection to the seller by the way.
As said before, no pedal will compensate for dodgy technique. Slap is as much about muting as it is about thumping and popping the strings. Also try practicing some rudimentary drum patterns like paradiddles (use your hands to tap on your legs) to get the left and right hands working alternately.
Reliced - a perfectly good instrument that has been left in the outside lane of the M25 for a couple of days to make it appear that it, and its' handler, have got plenty of miles on the clock.
Love 'em and miss Ian Dury loads. Would love to get some of their stuff in our set list but it's an uphill battle.
Have a go at Clever Trevor or If I was with a Woman. 2 of my favorites
Spent a Sunday afternoon in a pub in Highgate with Tony Hadleigh many years ago. A mate of mine was decorating his house and got me to price up some work he wanted doing on his Jag. He was a really down to earth bloke and a good laugh as well.
You should really contact the owner of the shop to let him/her know how crap the staff have been. People often work extremely hard to build up a business but the staff they employ really couldn't give a toss.
I've got a Digitech Bad Monkey sitting around. Quite happy to send it to you if you want to try it out. Then, you can buy it if you like it or send it back. PM me if you're interested. It's a good sounding pedal for a cheapie and can be modified to sound even better for bass.
I'm using the Diago Patch Factory kit which is essentially the same as the George L set. The reason I use these is that I can position the pedals I use most at the front of the board but run the whole lot in whatever order I like without making it look like a bowl of spaghetti.
Had a Mk VI and gigged it for years. Masses of power and absolutely bullet proof. It had a huge range of tone options as well. It did however feel like one end of it had been filled with concrete.